Examples with solutions for Addition and Subtraction of Directed Numbers: Solving the problem

Exercise #1

(+6)(+11)= (+6)-(+11)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form:

611= 6-11=

We'll locate the number 6 on the number line and from there we'll move 11 steps to the left:

111-2-2-2-1-1-1000-3-3-3-4-4-4666222333444555-5-5-5

The answer is minus 5.

Answer

5 -5

Exercise #2

(+8)+(+12)= (+8)+(+12)=

Video Solution

Step-by-Step Solution

Let's place 8 on the number line and move 12 steps to the right.

Let's note that our result is a positive number:

.888000+12

Let's solve the exercise:

8+12=20 8+12=20

Answer

20 20

Exercise #3

(8)(13)= (-8)-(-13)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

8+13= -8+13=

We'll use the substitution law and solve:

138=5 13-8=5

Answer

5 5

Exercise #4

(10)(+13)= (-10)-(+13)=

Video Solution

Step-by-Step Solution

Let's locate -10 on the number line and move 13 steps to the left.

Let's note that our result is a negative number:

000-10-10-10-13

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form and solve it:

1013=23 -10-13=-23

Answer

23 -23

Exercise #5

(8)+(12)= (-8)+(-12)=

Video Solution

Step-by-Step Solution

Let's locate -8 on the number line and move 12 steps to the left.

Let's note that our result is a negative number:

000-8-8-8-12

Let's remember the rule:

Now let's write the exercise in the appropriate form and solve it:

812=20 -8-12=-20

Answer

20 -20

Exercise #6

(8)+(+12)= (-8)+(+12)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

8+12= -8+12=

We'll draw a number line and place minus 8 on it, then move 12 steps to the right:

-1-1-1-4-4-4-3-3-3-2-2-2-5-5-5-6-6-6-8-8-8-7-7-7444000111222333

Therefore:

8+12=4 -8+12=4

Answer

4 4

Exercise #7

(x)(+3x)= (-x)-(+3x)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the following way:

x3x= -x-3x=

We'll mark negative x on the number line, and go 3 steps to the left:

-X-X-X-4X-4X-4X-3X-3X-3X-2X-2X-2X

The solution is:

x3x=4x -x-3x=-4x

Answer

4x -4x

Exercise #8

(+8)+(4.5)= (+8)+(-4.5)=

Video Solution

Step-by-Step Solution

Let's locate the number 8 on the number line and move 4.5 steps to the left from it:

000888

Let's remember the rule:

+(x)=x +(-x)=-x

Now let's write the problem in the appropriate form and solve it:

84.5=3.5 8-4.5=3.5

Answer

3.5 3.5

Exercise #9

(+567)(69)= (+567)-(-69)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

567+69= 567+69=

Let's solve the exercise vertically:

567+69636 567\\+69\\636

Answer

636 636

Exercise #10

(x)+(5x)= (-x)+(-5x)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(x)=x +(-x)=-x

Now let's write the exercise in the following way:

x5x= -x-5x=

We'll mark negative x on the number line, and move 5 steps to the left:

-X-X-X-4X-4X-4X-3X-3X-3X-2X-2X-2X-5X-5X-5X-6X-6X-6X

The solution is:

x5x=6x -x-5x=-6x

Answer

6x -6x

Exercise #11

(+x)+(+3x)= (+x)+(+3x)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

x+3x= x+3x=

We'll draw x on the number line, and move 3 steps to the right:

2X2X2X3X3X3X4X4X4X1X1X1X

The solution is:

x+3x=4x x+3x=4x

Answer

4x 4x

Exercise #12

(+x)(+4x)= (+x)-(+4x)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the following way:

x4x= x-4x=

We'll mark x on the number line, and go 4 steps to the left:

-X-X-X000XXX-2X-2X-2X-3X-3X-3X

The solution is:

x4x=3x x-4x=-3x

Answer

3x -3x

Exercise #13

(x)(6x)= (-x)-(-6x)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the following way:

x+6x= -x+6x=

We'll mark negative x on the number line, and move 6 steps to the right:

5X5X5X000-X-X-X

The solution is:

x+6x=5x -x+6x=5x

Answer

5x 5x

Exercise #14

Solve the following exercise:

(17)(77)= (-\frac{1}{7})-(-\frac{7}{7})=

Step-by-Step Solution

Let's position minus 17 \frac{1}{7} on the number line and move one step to the right, since 77=11=1 \frac{7}{7}=\frac{1}{1}=1

We should note that our result is a positive number:

000+1

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form and solve it:

17+1=67 -\frac{1}{7}+1=\frac{6}{7}

Answer

67 \frac{6}{7}

Exercise #15

(+14)+(234)= (+\frac{1}{4})+(2\frac{3}{4})=

Video Solution

Step-by-Step Solution

We will locate the number 14 \frac{1}{4} on the number line and move 234 2\frac{3}{4} steps to the right from it.

This means the resulting number will be positive:

Let's solve the exercise:

14+234=3 \frac{1}{4}+2\frac{3}{4}=3

Answer

3

Exercise #16

(+7)(6.7)= (+7)-(-6.7)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form and solve it:

7+6.7=13.7 7+6.7=13.7

Answer

13.7 13.7

Exercise #17

(0.43)(0.87)= (-0.43)-(-0.87)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(x)=+x -(-x)=+x

Now let's write the exercise in the appropriate form:

0.43+0.87= -0.43+0.87=

We'll use the distributive property and solve the exercise step by step:

0.870.430.44 0.87\\-0.43\\0.44

Answer

0.44 0.44

Exercise #18

(+0.18)+(+0.88)= (+0.18)+(+0.88)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(+x)=+x +(+x)=+x

Now let's write the exercise in the following way:

0.18+0.88= 0.18+0.88=

Since we are multiplying two positive numbers, the result will be positive.

Therefore:

0.18+0.881.06 0.18\\+0.88\\1.06

Answer

1.06 1.06

Exercise #19

(+0.76)(+13.04)= (+0.76)-(+13.04)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

(+x)=x -(+x)=-x

Now let's write the exercise in the appropriate form:

0.7613.04= 0.76-13.04=

We'll solve the exercise vertically, but keep in mind that the final result will be negative since we are subtracting a smaller number from a larger number:

13.040.7612.28 13.04\\-0.76\\12.28

Remember that the answer is a negative number, which means:

12.28 -\text{12}.28

Answer

12.28 -12.28

Exercise #20

(0.73)+(13.07)= (-0.73)+(-13.07)=

Video Solution

Step-by-Step Solution

Let's remember the rule:

+(x)=x +(-x)=-x

Now let's write the exercise in the appropriate form:

0.7313.07= -0.73-13.07=

Since we are subtracting a larger number from a smaller number, the result will be negative.

We'll combine the two numbers together vertically, but remember that the result will be negative:

0.73+13.0713.80 0.73\\+13.07\\13.80

Therefore, the answer is:

0.7313.07=13.8 -0.73-13.07=-13.8

Answer

13.8 -13.8