#### Solved Examples and Worksheet for Inverse Relationship between Addition and Subtraction

Q1Complete the basic fact sentence.
If 18 - 6 = 12, then 12 + 6 = _____.

A. 6
B. 18
C. 16
D. 72

Step: 1
18 - 6 = 12
Step: 2
18 - 6 + 6 = 12 + 6
[Add 6 to both sides of the equation.]
Step: 3
18 = 12 + 6
[Simplify.]
Step: 4
So, 12 + 6 = 18.
Q2Choose an opposite number sentence for 16 + 12 = 28.

A. 28 + 12 = 16
B. 12 - 28 = 16
C. 28 - 12 = 16
D. 12 + 16 = 28

Step: 1
Opposite number sentence for '16 + 12 = 28' is '28 - 12 = 16'
[Inverse relationship.]
Correct Answer is :   28 - 12 = 16
Q3Complete the basic fact.

If 14 + 8 = 22, then 22 - 8 = _____.

A. 14
B. 2
C. 4
D. 48

Step: 1
Original number sentence is 14 + 8 = 22.
Step: 2
The opposite number sentence is 22 - 8 = 14 or 22 - 14 = 8.
Step: 3
So, if 14 + 8 = 22, then 22 - 8 = 14
Q4Complete the basic fact.

If 50 - 2 = 48, then 48 + 2 = _____.

A. 50
B. 96
C. 46
D. 28

Step: 1
If '50 - 2 = 48', then '48 + 2 = 50'.
[Inverse relationship.]
Q5Choose an opposite number sentence for 26 + 2 = 28.

A. 28 + 2 = 30
B. 28 + 26 = 54
C. 28 - 26 = 2
D. 26 - 26 = 0

Step: 1
26 + 2 = 28
[Given.]
Step: 2
The opposite number sentence for this is 28 - 26 = 2 or 28 - 2 = 26
Correct Answer is :   28 - 26 = 2
Q6Identify the opposite number sentence for 20 + 12 = 32.

A. 12 + 12 = 24
B. 32 + 12 = 44
C. 12 + 20 = 32
D. 32 - 12 = 20

Step: 1
Opposite number sentence for '20 + 12 = 32' is '32 - 12 = 20'.
[Inverse relationship.]
Correct Answer is :   32 - 12 = 20
Q7Identify the opposite number sentence for 6 + 5 = 11.
A. 6 - 5 = 1
B. 11 + 6 = 17
C. 11 - 5 = 6
D. 5 + 5 = 10

Step: 1
Original number sentence is 6 + 5 = 11.
Step: 2
The opposite number sentence is 11 - 5 = 6 or 11 - 6 = 5.
Correct Answer is :   11 - 5 = 6
Q8Choose an opposite number sentence for 21 + 17 = 38.

A. 38 - 21 = 17
B. 38 + 21 = 49
C. 38 + 17 = 55
D. 38 + 38 = 76

Step: 1
21 + 17 = 38
[Given.]
Step: 2
The opposite number sentence for this is 38 - 21 = 17 or 38 - 17 = 21.
Correct Answer is :   38 - 21 = 17

A. 4 + 8 = 12
B. 8 + 8 = 12
C. 8 - 4 = 12
D. 4 + 4 = 12

Step: 1
We know that 4 + 8 = 12.
Step: 2
The opposite number sentence for this is 12 - 8 = 4.
Step: 3
So, 4 + 8 = 12 will help us solve the problem.
The other three number sentences listed are wrong.
4 + 4 is not equal to 12.
8 + 8 is not equal to 12.
8 - 4 is not equal to 12.
Correct Answer is :   4 + 8 = 12
A. 5 + 5 = 14
B. 5 + 7 = 14
C. 5 + 8 = 14
D. 5 + 9 = 14

Step: 1
We know that 5 + 9 = 14.
Step: 2
The opposite number sentence for this is 14 - 5 = 9.
Step: 3
So, 5 + 9 = 14 will help us solve the problem.
The other three number sentences listed are wrong.
5 + 7 is not equal to 14.
5 + 5 is not equal to 14.
5 + 8 is not equal to 14.
Correct Answer is :   5 + 9 = 14