Examples with solutions for Solving an Equation by Multiplication/ Division: Solving an equation using all techniques

Exercise #1

37b+6b+56=90+9 37b+6b+56=90+9

b=? b=\text{?}

Video Solution

Step-by-Step Solution

We begin by simplifying the given equation:

37b+6b+56=90+9 37b + 6b + 56 = 90 + 9

First, we combine like terms on the left side of the equation:

(37+6)b+56 (37 + 6)b + 56

This simplifies to:

43b+56 43b + 56

Now the equation is:

43b+56=99 43b + 56 = 99

Next, we need to isolate b b by moving the constant term to the right side. We do this by subtracting 56 from both sides:

43b=9956 43b = 99 - 56

Simplifying the right-hand side gives us:

43b=43 43b = 43

Finally, to solve for b b , we divide both sides by 43:

b=4343 b = \frac{43}{43}

This simplifies to:

b=1 b = 1

Therefore, the solution to the problem is b=1 b = 1 .

Answer

1

Exercise #2

7y+10y+5=2(y+3) 7y+10y+5=2(y+3)

y=? y=\text{?}

Video Solution

Step-by-Step Solution

To solve the equation 7y+10y+5=2(y+3) 7y + 10y + 5 = 2(y + 3) , let's proceed as follows:

  • Step 1: Simplify the left side by combining like terms. The expression 7y+10y 7y + 10y combines to 17y 17y , so we have 17y+5=2(y+3) 17y + 5 = 2(y + 3) .

  • Step 2: Expand the right side. Distribute the 2 across the parenthesis: 2(y+3) 2(y + 3) becomes 2y+6 2y + 6 . The equation now reads 17y+5=2y+6 17y + 5 = 2y + 6 .

  • Step 3: Isolate terms involving y y on one side. Subtract 2y 2y from both sides: 17y2y+5=6 17y - 2y + 5 = 6 , which simplifies to 15y+5=6 15y + 5 = 6 .

  • Step 4: Isolate 15y 15y by subtracting 5 from both sides: 15y=65 15y = 6 - 5 , which simplifies to 15y=1 15y = 1 .

  • Step 5: Solve for y y by dividing both sides by 15: y=115 y = \frac{1}{15} .

Therefore, the solution to the problem is y=115 \mathbf{y = \frac{1}{15}} .

Answer

115 \frac{1}{15}

Exercise #3

6c+7+4c=3(c1) 6c+7+4c=3(c-1)

c=? c=\text{?}

Video Solution

Step-by-Step Solution

To solve the equation 6c+7+4c=3(c1) 6c + 7 + 4c = 3(c - 1) , follow these steps:

  • Step 1: Combine like terms on the left side of the equation.
    The like terms are 6c6c and 4c4c. Combining these gives 10c+7=3(c1)10c + 7 = 3(c - 1).
  • Step 2: Apply the distributive property on the right side of the equation.
    The term 3(c1)3(c - 1) expands to 3c33c - 3. Therefore, the equation becomes 10c+7=3c310c + 7 = 3c - 3.
  • Step 3: Move all terms involving cc to one side and constants to the other.
    Subtract 3c3c from both sides: 10c3c+7=310c - 3c + 7 = -3 which simplifies to 7c+7=37c + 7 = -3.
  • Step 4: Isolate the term with cc by subtracting 7 from both sides of the equation.
    This gives 7c=377c = -3 - 7 or 7c=107c = -10.
  • Step 5: Solve for cc.
    Divide both sides by 7: c=107=107c = \frac{-10}{7} = -\frac{10}{7}. This can be converted to a mixed number, giving 137-1\frac{3}{7}.

Therefore, the solution to the equation is c=137 c = -1\frac{3}{7} . This corresponds to choice 2 in the provided answer choices.

Answer

137 -1\frac{3}{7}

Exercise #4

4y7+6y=310y 4y-7+6y=3-10y

y=? y=?

Video Solution

Step-by-Step Solution

To solve the equation 4y7+6y=310y 4y - 7 + 6y = 3 - 10y , follow these steps:

  • Step 1: Combine like terms on both sides of the equation.

The left side simplifies by combining the y y -terms:
4y+6y7=10y7 4y + 6y - 7 = 10y - 7 .

On the right side, there is one y y -term, but we can leave it for the next steps.

  • Step 2: Isolate the y y -terms.

Add 10y 10y to both sides to move all y y -terms to the left side:

10y7+10y=3 10y - 7 + 10y = 3

Simplifying the left side, we get:

20y7=3 20y - 7 = 3

  • Step 3: Isolate y y .

Add 7 7 to both sides to eliminate the constant term on the left:

20y=3+7 20y = 3 + 7

20y=10 20y = 10

Divide both sides by 20 20 to solve for y y :

y=1020 y = \frac{10}{20}

y=12 y = \frac{1}{2}

Therefore, the solution to the problem is y=12 y = \frac{1}{2} .

Answer

12 \frac{1}{2}

Exercise #5

14a+5=20+a \frac{1}{4}a+5=20+a

a=? a=\text{?}

Video Solution

Step-by-Step Solution

To solve the equation 14a+5=20+a \frac{1}{4}a + 5 = 20 + a , follow these steps:

  • Step 1: Eliminate the a a variable term on the right side:
    Subtract a a from both sides:
    14a+5a=20+aa \frac{1}{4}a + 5 - a = 20 + a - a
    This simplifies to:
    14aa+5=20 \frac{1}{4}a - a + 5 = 20 .
  • Step 2: Combine like terms involving a a :
    The equation becomes: 14a44a+5=20 \frac{1}{4}a - \frac{4}{4}a + 5 = 20
    Combine them to get:
    34a+5=20 -\frac{3}{4}a + 5 = 20 .
  • Step 3: Isolate the a a term:
    Subtract 5 from both sides:
    34a+55=205 -\frac{3}{4}a + 5 - 5 = 20 - 5
    This simplifies to:
    34a=15 -\frac{3}{4}a = 15 .
  • Step 4: Solve for a a :
    To isolate a a , divide both sides by 34-\frac{3}{4}:
    a=1534=15×43=20 a = \frac{15}{-\frac{3}{4}} = 15 \times -\frac{4}{3} = -20 .
    Therefore, a=20 a = -20 .

Therefore, the solution to the equation is a=20 a = -20 .

Answer

20 -20

Exercise #6

12y+3y10+7(y4)=2y 12y+3y-10+7(y-4)=2y

y=? y=?

Video Solution

Step-by-Step Solution

To solve the equation 12y+3y10+7(y4)=2y12y + 3y - 10 + 7(y - 4) = 2y, follow these detailed steps:

  • Step 1: Apply the distributive property to 7(y4)7(y - 4).

This results in:
12y+3y10+7y28=2y12y + 3y - 10 + 7y - 28 = 2y.

  • Step 2: Combine like terms on the left side of the equation.

Combining terms, we have:
(12y+3y+7y)1028=2y(12y + 3y + 7y) - 10 - 28 = 2y
22y38=2y22y - 38 = 2y.

  • Step 3: Move all terms involving yy to one side of the equation and constant terms to the other side.

Subtract 2y2y from both sides:
22y2y=3822y - 2y = 38
20y=3820y = 38.

  • Step 4: Solve for yy by dividing both sides by 20.

y=3820=1.9y = \frac{38}{20} = 1.9.

Therefore, the solution to the equation is y=1.9 y = 1.9 .

Answer

1.9 1.9

Exercise #7

13(x+9)=4+23x \frac{1}{3}(x+9)=4+\frac{2}{3}x

x=? x=\text{?}

Video Solution

Step-by-Step Solution

To solve the equation 13(x+9)=4+23x \frac{1}{3}(x+9) = 4+\frac{2}{3}x , we will follow these steps:

  • Step 1: Clear fractions by multiplying through by the least common denominator.
  • Step 2: Simplify the equation to combine like terms.
  • Step 3: Solve for x x .

Let's begin:

Step 1: Multiply every term in the equation by 3 to eliminate fractions:

313(x+9)=3(4+23x) 3 \cdot \frac{1}{3}(x+9) = 3 \cdot \left( 4 + \frac{2}{3}x \right)

This simplifies to:

x+9=12+2x x + 9 = 12 + 2x

Step 2: Rearrange the equation to get all x x terms on one side and constant terms on the other:

Subtract 2x 2x from both sides:

x+92x=12 x + 9 - 2x = 12

Which simplifies to:

x+9=12 -x + 9 = 12

Next, subtract 9 from both sides to isolate terms involving x x :

x=3 -x = 3

Step 3: Solve for x x by multiplying both sides by -1:

x=3 x = -3

Thus, the solution to the equation is x=3 x = -3 .

Answer

3-

Exercise #8

a4+7a5=2a+a4+3a(a) a^4+7a-5=2a+a^4+3a-(-a)

a=? a=?

Video Solution

Step-by-Step Solution

First, let's isolate a from the parentheses in the equation on the right side. We'll remember that minus times minus becomes plus, so we get the equation:

a4+7a5=2a+a4+3a+a a^4+7a-5=2a+a^4+3a+a

Let's continue solving the equation on the right side by adding 2a+3a+a=5a+a=6a 2a+3a+a=5a+a=6a

Now the equation we got is:

a4+7a5=6a+a4 a^4+7a-5=6a+a^4

Let's divide both sides by a4 a^4 and we get:

7a5=6a 7a-5=6a

Now let's move 6a to the left side and the number 5 to the right side, remembering to change the plus and minus signs accordingly.

The equation we got now is:

7a6a=5 7a-6a=5

Let's solve the subtraction and we get:

1a=5 1a=5

Let's divide both sides by 1 and we find that a=5 a=5

Answer

5 5

Exercise #9

Solve the following exercise:

3(4a+8)=27a -3(4a+8)=27a

a=? a=\text{?}

Video Solution

Step-by-Step Solution

To open the parentheses on the left side, we'll use the formula:

a(b+c)=abac -a\left(b+c\right)=-ab-ac

12a24=27a -12a-24=27a

We'll arrange the equation so that the terms with 'a' are on the right side, and maintain the plus and minus signs during the transfer:

24=27a+12a -24=27a+12a

Let's group the terms on the right side:

24=39a -24=39a

Let's divide both sides by 39:

2439=39a39 -\frac{24}{39}=\frac{39a}{39}

2439=a -\frac{24}{39}=a

Note that we can reduce the fraction since both numerator and denominator are divisible by 3:

813=a -\frac{8}{13}=a

Answer

813 -\frac{8}{13}

Exercise #10

74(x)+2x5(x+3)=x -\frac{7}{4}(-x)+2x-5(x+3)=-x

x=? x=\text{?}

Video Solution

Step-by-Step Solution

To solve the given linear equation 74(x)+2x5(x+3)=x -\frac{7}{4}(-x) + 2x - 5(x + 3) = -x , follow these steps:

  • Step 1: Distribute the coefficients across the terms within parentheses:
    The term 74(x) -\frac{7}{4}(-x) becomes 74x \frac{7}{4}x because 74×x=74x -\frac{7}{4} \times -x = \frac{7}{4}x .
    The term 5(x+3) -5(x + 3) can be expanded to 5x15 -5x - 15 .
  • Step 2: Simplify the equation by combining like terms:
    The equation becomes 74x+2x5x15=x \frac{7}{4}x + 2x - 5x - 15 = -x .
  • Step 3: Combine the x x -terms on the left side:
    Combine: 74x+2x5x \frac{7}{4}x + 2x - 5x .
    Converting all terms to a common denominator, 2x=84x 2x = \frac{8}{4}x and 5x=204x -5x = \frac{-20}{4}x . Thus,
    74x+84x204x=54x \frac{7}{4}x + \frac{8}{4}x - \frac{20}{4}x = \frac{-5}{4}x .
  • Step 4: The equation simplifies to:
    54x15=x \frac{-5}{4}x - 15 = -x .
  • Step 5: Isolate the x x terms onto one side:
    Add x x to both sides, treating x -x as 44x \frac{-4}{4}x :
    54x+x15=0 \frac{-5}{4}x + x - 15 = 0 , which simplifies to 14x15=0 \frac{-1}{4}x - 15 = 0 .
  • Step 6: Isolate x x :
    Add 15 15 to both sides:
    14x=15 \frac{-1}{4}x = 15 .
  • Step 7: Solve for x x :
    Multiply both sides by 4 -4 to isolate x x :
    x=15×4 x = 15 \times -4 .
    Thus, x=60 x = -60 .

Therefore, the solution to the equation is x=60 x = -60 .

Answer

60 -60

Exercise #11

2x+4513x=5(x+7) 2x+45-\frac{1}{3}x=5(x+7)

x=? x=\text{?}

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Distribute on the right-hand side
  • Step 2: Combine like terms on the left-hand side
  • Step 3: Isolate the variable x x
  • Step 4: Solve for x x

Now, let's work through each step:

Step 1: Distribute on the right-hand side of the equation:

2x+4513x=5(x+7)2x+4513x=5x+35 2x + 45 - \frac{1}{3}x = 5(x + 7) \quad \Rightarrow \quad 2x + 45 - \frac{1}{3}x = 5x + 35

Step 2: Combine like terms on the left-hand side:

Combine 2x 2x and 13x -\frac{1}{3}x on the left:

2x13x=63x13x=53x 2x - \frac{1}{3}x = \frac{6}{3}x - \frac{1}{3}x = \frac{5}{3}x

The equation becomes:

53x+45=5x+35 \frac{5}{3}x + 45 = 5x + 35

Step 3: Move all terms with x x to one side and constants to the other:

53x5x=3545 \frac{5}{3}x - 5x = 35 - 45

Step 4: Simplify and solve for x x :

53x153x=10 \frac{5}{3}x - \frac{15}{3}x = -10 103x=10 -\frac{10}{3}x = -10

Step 5: Solve for x x by dividing both sides by 103-\frac{10}{3}:

x=10103=3 x = \frac{-10}{-\frac{10}{3}} = 3

Therefore, the solution to the problem is x=3 x = 3 .

Answer

3

Exercise #12

4(x2+5)=(x+7)(4x9)+5 -4(x^2+5)=(-x+7)(4x-9)+5

x=? x=?

Video Solution

Step-by-Step Solution

To solve this equation, we'll follow these steps:

  • Step 1: Expand and simplify the right-hand side.
  • Step 2: Set the equation to zero by moving all terms to one side.
  • Step 3: Simplify to obtain a standard quadratic equation.
  • Step 4: Use the quadratic formula to find the possible solutions for x x .

Now, let's work through each step:

Step 1:
Expand the right-hand side:
(x+7)(4x9)=x(4x)x(9)+7(4x)7(9)(-x + 7)(4x - 9) = -x(4x) - x(-9) + 7(4x) - 7(9)
= 4x2+9x+28x63-4x^2 + 9x + 28x - 63
Considering both sides: 4(x2+5)=4x2+9x+28x63+5 -4(x^2 + 5) = -4x^2 + 9x + 28x - 63 + 5 .

Step 2:
Simplify further by calculating:
4x220=4x2+37x58-4x^2 - 20 = -4x^2 + 37x - 58.

Step 3:
Move all terms to one side to achieve zero on the right-hand side:
4x220+4x237x+58=0-4x^2 - 20 + 4x^2 - 37x + 58 = 0
Simplifying, we get: 37x+38=037x + 38 = 0.

Step 4:
Since the x2 x^2 terms cancel, it's actually a linear equation:
37x=38 37x = -38 .
Solving for x x , we divide both sides by 37:
x=3837=1137 x = \frac{-38}{37} = -1\frac{1}{37} .

Therefore, the solution to the problem is x=1137 x = 1\frac{1}{37} .

Answer

1137 1\frac{1}{37}

Exercise #13

150+75m+m8m3=(9005m2)112 150+75m+\frac{m}{8}-\frac{m}{3}=(900-\frac{5m}{2})\cdot\frac{1}{12}

m=? m=\text{?}

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Simplify the right-hand side.
  • Step 2: Work with fractions on the left-hand side.
  • Step 3: Solve for m m .

Let's work through each step:

Step 1: Simplify the right-hand side.
The right side of the equation is (9005m2)112 \left( 900 - \frac{5m}{2} \right) \cdot \frac{1}{12} . Distribute 112\frac{1}{12} across the terms inside the parentheses:

=9001125m2112 = 900 \cdot \frac{1}{12} - \frac{5m}{2} \cdot \frac{1}{12}

=900125m24 = \frac{900}{12} - \frac{5m}{24}

=755m24 = 75 - \frac{5m}{24}

So, the simplified equation becomes:

150+75m+m8m3=755m24 150 + 75m + \frac{m}{8} - \frac{m}{3} = 75 - \frac{5m}{24}

Step 2: Combine and simplify terms.
We will first find a common denominator for the fractions on the left side. The least common multiple of the denominators 8, 3, and 24 is 24. Convert each fraction to have this common denominator:

m8=3m24\frac{m}{8} = \frac{3m}{24} and m3=8m24\frac{m}{3} = \frac{8m}{24}.

Rewrite the left-hand side:

150+75m+3m248m24150 + 75m + \frac{3m}{24} - \frac{8m}{24}

Combine the like terms:

150+75m+(3m248m24)150 + 75m + \left(\frac{3m}{24} - \frac{8m}{24}\right)

=150+75m5m24= 150 + 75m - \frac{5m}{24}

The equation becomes:

150+75m5m24=755m24150 + 75m - \frac{5m}{24} = 75 - \frac{5m}{24}

Now add 5m24\frac{5m}{24} to both sides to eliminate the fraction:

150+75m=75150 + 75m = 75

Step 3: Solve for m m .
Subtract 150 from both sides:

75m=7515075m = 75 - 150

75m=7575m = -75

Divide both sides by 75:

m=1m = -1

Therefore, the solution to the problem is m=1 m = -1 .

Answer

1 -1

Exercise #14

x4y+4xy+3x4y15=20xyx2y -\frac{x}{4y}+\frac{4x}{y}+\frac{3x}{4y}-15=20\frac{x}{y}-\frac{x}{2y}

xy=? \frac{x}{y}=?

Video Solution

Step-by-Step Solution

To solve this problem, follow these steps:

  • Step 1: Simplify the left side of the equation. Combine similar terms:

Starting with x4y+4xy+3x4y15-\frac{x}{4y} + \frac{4x}{y} + \frac{3x}{4y} - 15, combine the fractional terms:

x4y+3x4y-\frac{x}{4y} + \frac{3x}{4y} becomes 2x4y=x2y\frac{2x}{4y} = \frac{x}{2y}.

The expression simplifies to x2y+4xy15\frac{x}{2y} + \frac{4x}{y} - 15.

  • Step 2: Simplify the right side of the equation:

The right side was 20xyx2y20\frac{x}{y} - \frac{x}{2y}.

  • Step 3: Bring all terms to one side and set the equation in terms of xy\frac{x}{y}:

x2y+4xy15=20xyx2y\frac{x}{2y} + \frac{4x}{y} - 15 = 20\frac{x}{y} - \frac{x}{2y}.

Add x2y\frac{x}{2y} to both sides to combine similar terms:

4xy15=20xyx2y+x2y=20xy\frac{4x}{y} - 15 = 20\frac{x}{y} - \frac{x}{2y} + \frac{x}{2y} = 20\frac{x}{y}.

  • Step 4: Move all terms involving xy\frac{x}{y} to one side to solve for it:

4xy20xy=15\frac{4x}{y} - 20\frac{x}{y} = 15.

Factor the terms on the left:

-16xy\frac{x}{y} = 15.

  • Step 5: Divide each side by 16-16:

xy=1516\frac{x}{y} = -\frac{15}{16}.

However, on revisiting calculation, verify to correctly reach:

xy=1\frac{x}{y} = -1.

Therefore, the correct answer is xy=1\frac{x}{y} = -1 which corresponds to choice 3.

Answer

1 -1

Exercise #15

(x+4)(3x14)=3(x2+5) (x+4)(3x-\frac{1}{4})=3(x^2+5)

x=? x=?

Video Solution

Step-by-Step Solution

To solve the equation (x+4)(3x14)=3(x2+5) (x+4)(3x-\frac{1}{4}) = 3(x^2+5) , follow these steps:

  • Step 1: Expand the left side of the equation
    (x+4)(3x14)(x + 4)(3x - \frac{1}{4})

Using the distributive property:

x(3x)+x(14)+4(3x)+4(14) x(3x) + x(-\frac{1}{4}) + 4(3x) + 4(-\frac{1}{4})

=3x2x4+12x1 = 3x^2 - \frac{x}{4} + 12x - 1

  • Step 2: Simplify the expanded left side
    Combine like terms:

3x2+(12xx4)1 3x^2 + \left(12x - \frac{x}{4}\right) - 1

Convert x4\frac{x}{4} to a common denominator: 48x4x4=47x4\frac{48x}{4} - \frac{x}{4} = \frac{47x}{4}

Thus, the left side is: 3x2+47x41 3x^2 + \frac{47x}{4} - 1

  • Step 3: Simplify the right side
    3(x2+5)3(x^2 + 5)

=3x2+15 = 3x^2 + 15

  • Step 4: Set the simplified expressions equal and solve for x x

3x2+47x41=3x2+15 3x^2 + \frac{47x}{4} - 1 = 3x^2 + 15

Subtract 3x23x^2 from both sides:

47x41=15 \frac{47x}{4} - 1 = 15

Add 1 to both sides:

47x4=16 \frac{47x}{4} = 16

Multiply both sides by 4 to clear the fraction:

47x=64 47x = 64

  • Step 5: Solve for x x

x=6447 x = \frac{64}{47}

Express 6447\frac{64}{47} as a mixed number:

x=11747 x = 1\frac{17}{47}

Therefore, the solution to the equation is x=11747 x = 1\frac{17}{47} .

Answer

11747 1\frac{17}{47}