Examples with solutions for Solving Equations by using Addition/ Subtraction: Solving an equation by multiplying/dividing both sides

Exercise #1

Solve for X:

7x3=4x+9 7x - 3 = 4x + 9

Video Solution

Step-by-Step Solution

To solve the equation 7x3=4x+9 7x - 3 = 4x + 9 , follow these steps:

1. Subtract 4x 4x from both sides to get:

7x4x3=9 7x - 4x - 3 = 9

2. Simplify the equation:

3x3=9 3x - 3 = 9

3. Add 3 3 to both sides:

3x=12 3x = 12

4. Divide both sides by 3 3 :

x=4 x=4

Answer

4

Exercise #2

10+9x=91 10+9x=91

How much is X worth?

Video Solution

Step-by-Step Solution

To solve the equation 10+9x=91 10 + 9x = 91 , we'll follow these steps:

  • Step 1: Eliminate the constant term on the left side by subtracting 10 from both sides of the equation.

10+9x10=9110 10 + 9x - 10 = 91 - 10 9x=81 9x = 81

  • Step 2: Solve for x x by dividing each side of the equation by the coefficient of x x , which is 9.

9x9=819 \frac{9x}{9} = \frac{81}{9} x=9 x = 9

Hence, the value of x x is 9 9 .

Answer

9 9

Exercise #3

5x+6=56 5x+6=56

How much is X X worth?

Video Solution

Step-by-Step Solution

To solve the equation 5x+6=56 5x + 6 = 56 , we will follow these steps:

  • Step 1: Subtract 6 from both sides of the equation to eliminate the constant term on the left-hand side.
  • Step 2: Simplify the resulting equation.
  • Step 3: Divide both sides by 5 to isolate x x .

Now, perform each step:

Step 1: Subtract 6 from both sides:
5x+66=566 5x + 6 - 6 = 56 - 6

Step 2: Simplify both sides:
5x=50 5x = 50

Step 3: Divide both sides by 5 to solve for x x :
x=505 x = \frac{50}{5}

Step 4: Simplify the division:

x=10 x = 10

Therefore, the solution to the problem is x=10 x = 10 .

Answer

10 10

Exercise #4

4a+524+a=2a 4a+5-24+a=-2a

a=? a=?

Video Solution

Step-by-Step Solution

To solve the equation 4a+524+a=2a 4a + 5 - 24 + a = -2a , follow these steps:

  • Step 1: Start by combining like terms on the left side of the equation:

4a+a+524=2a 4a + a + 5 - 24 = -2a

This simplifies to:

5a19=2a 5a - 19 = -2a

  • Step 2: Move all terms involving a a to one side of the equation and constant terms to the other side:

Add 2a 2a to both sides to collect all terms with a a :

5a+2a=19 5a + 2a = 19

This simplifies to:

7a=19 7a = 19

  • Step 3: Solve for a a by dividing both sides by 7:

a=197 a = \frac{19}{7}

Thus, the value of a a is 197 \frac{19}{7} , which can be written as a mixed number:

a=257 a = 2\frac{5}{7} .

Upon verifying with the given choices, the correct answer is choice 1: 257 2\frac{5}{7} .

Answer

257 2\frac{5}{7}

Exercise #5

m+3m17m+6=20 m+3m-17m+6=-20

m=? m=\text{?}

Video Solution

Step-by-Step Solution

To solve the problem, we will use the following steps:

  • Step 1: Simplify the equation by combining like terms.
  • Step 2: Isolate the variable m m using algebraic methods.
  • Step 3: Solve for m m and verify the solution.

Let's begin:

Step 1: Simplify the equation m+3m17m+6=20 m + 3m - 17m + 6 = -20 .
Combine the coefficients of m m :

(1+317)m+6=20 (1 + 3 - 17)m + 6 = -20

This simplifies to:

13m+6=20 -13m + 6 = -20

Step 2: Isolate m m .
Subtract 6 from both sides:

13m+66=206 -13m + 6 - 6 = -20 - 6

Simplifies to:

13m=26 -13m = -26

Step 3: Solve for m m by dividing both sides by -13:

m=2613 m = \frac{-26}{-13}

The division simplifies to:

m=2 m = 2

Therefore, the solution to the problem is m=2 m = 2 , which corresponds to choice 2 in the given options.

Answer

2

Exercise #6

Solve for X:

5x+4=7x 5x+4=7x

Video Solution

Step-by-Step Solution

To solve the equation 5x+4=7x 5x + 4 = 7x , we will proceed as follows:

  • Step 1: Subtract 5x 5x from both sides to simplify the equation.

The equation is:
5x+45x=7x5x 5x + 4 - 5x = 7x - 5x

This simplifies to:
4=2x 4 = 2x

  • Step 2: To solve for x x , divide both sides by 2 to isolate x x .

Perform the division:
42=2x2 \frac{4}{2} = \frac{2x}{2}

This gives us:
2=x 2 = x

Therefore, the solution to the equation is x=2 x = 2 .

Answer

2 2

Exercise #7

2x+4+283x=x 2x+4+28-3x=x

x=? x=?

Video Solution

Step-by-Step Solution

To solve this problem, we will simplify and solve the linear equation step-by-step:

1. Start with the given equation:
2x+4+283x=x 2x + 4 + 28 - 3x = x

2. Combine like terms on the left side:
(2x3x)+4+28=x (2x - 3x) + 4 + 28 = x

3. This simplifies to:
x+32=x -x + 32 = x

4. Move all terms involving x x to one side of the equation by adding x x to both sides:
32=2x 32 = 2x

5. Finally, divide both sides by 2 to solve for x x :
x=322 x = \frac{32}{2}

6. Simplify to get the solution:
x=16 x = 16

Therefore, the solution to the problem is x=16 \mathbf{x = 16} .

Answer

16

Exercise #8

3x+4+8x15=0 3x+4+8x-15=0

x=? x=\text{?}

Video Solution

Step-by-Step Solution

To solve the equation 3x+4+8x15=0 3x + 4 + 8x - 15 = 0 , we begin by combining the terms that involve x x and the constant terms:

Step 1: Combine like terms.
The terms involving x x are 3x 3x and 8x 8x . Adding these yields:

11x 11x

The constant terms are +4 +4 and 15-15. Combining these gives:

+415=11 +4 - 15 = -11

Thus, the equation becomes:

11x11=0 11x - 11 = 0

Step 2: Solve for x x .
To isolate x x , add 11 to both sides of the equation:

11x11+11=0+11 11x - 11 + 11 = 0 + 11 11x=11 11x = 11

Now, divide both sides by 11:

x=1111 x = \frac{11}{11} x=1 x = 1

Therefore, the solution to the equation is x=1 x = 1 .

Answer

1 1

Exercise #9

Solve for X:

x+5=11x x+5=11x

Video Solution

Step-by-Step Solution

Let's solve the equation x+5=11x x + 5 = 11x step-by-step.

  • Step 1: Isolate the variable x x
    Start by getting all terms involving x x on one side of the equation. We can do this by subtracting x x from both sides:
    x+5x=11xx x + 5 - x = 11x - x
  • This simplifies to:
    5=10x 5 = 10x
  • Step 2: Solve for x x
    Now, divide both sides of the equation by 10 to solve for x x :
    510=10x10 \frac{5}{10} = \frac{10x}{10}
  • This further simplifies to:
    x=12 x = \frac{1}{2}

Therefore, the solution to the equation x+5=11x x + 5 = 11x is x=12 x = \frac{1}{2} .

Answer

12 \frac{1}{2}

Exercise #10

Solve for X:

3x+8=7x12 -3x+8=7x-12

Video Solution

Step-by-Step Solution

We will solve the equation step by step:

Given equation:
3x+8=7x12 -3x + 8 = 7x - 12

  • Step 1: Move all x x -terms to one side by adding 3x 3x to both sides.
    3x+3x+8=7x+3x12 -3x + 3x + 8 = 7x + 3x - 12
    This simplifies to:
    8=10x12 8 = 10x - 12
  • Step 2: Move constant terms to the opposite side by adding 12 12 to both sides.
    8+12=10x12+12 8 + 12 = 10x - 12 + 12
    Which simplifies to:
    20=10x 20 = 10x
  • Step 3: Solve for x x by dividing both sides by 10 10 .
    2010=10x10 \frac{20}{10} = \frac{10x}{10}
    This gives us:
    x=2 x = 2

Therefore, the solution to the equation is x=2 x = 2 .

Answer

2 2

Exercise #11

Solve for X:

5x8=10x+22 5x-8=10x+22

Video Solution

Step-by-Step Solution

First, we arrange the two sections so that the right side contains the values with the coefficient x and the left side the numbers without the x

Let's remember to maintain the plus and minus signs accordingly when we move terms between the sections.

First, we move a5x 5x to the right section and then the 22 to the left side. We obtain the following equation:

822=10x5x -8-22=10x-5x

We subtract both sides accordingly and obtain the following equation:

30=5x -30=5x

We divide both sections by 5 and obtain:

6=x -6=x

Answer

6 -6

Exercise #12

2y1yy+4=8y 2y\cdot\frac{1}{y}-y+4=8y

y=? y=\text{?}

Video Solution

Step-by-Step Solution

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

  • Simplify the term 2y1y 2y \cdot \frac{1}{y}
  • Rearrange the equation to group similar terms
  • Solve for y y

Now, let's work through each step:

Step 1: Simplify the expression 2y1y 2y \cdot \frac{1}{y} .

The term 2y1y 2y \cdot \frac{1}{y} simplifies directly to 2 2 since y y in the numerator and denominator cancel each other out assuming y0 y \neq 0 . Therefore, the equation becomes:

2y+4=8y 2 - y + 4 = 8y

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

2+4=6 2 + 4 = 6 , so the equation now is 6y=8y 6 - y = 8y .

Step 3: Rearrange the equation to isolate y y on one side. Add y y to both sides to get rid of the negative y y :

6=8y+y 6 = 8y + y

This simplifies to:

6=9y 6 = 9y

Step 4: Solve for y y by dividing both sides by 9:

y=69 y = \frac{6}{9}

Simplify the fraction to get:

y=23 y = \frac{2}{3}

Therefore, the solution to the problem is 23 \frac{2}{3} .

Answer

23 \frac{2}{3}