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Rewriting a Subtraction Problem as an Addition Problem Help

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By — McGraw-Hill Professional
Updated on Sep 27, 2011

Rewriting a Subtraction Problem as an Addition Problem

Sometimes in algebra it is easier to think of a subtraction problem as an addition problem. One advantage to this is that you can rearrange the terms in an addition problem but not a subtraction problem: 3 + 4 = 4 + 3 but 4 – 3 ≠ 3 – 4. The minus sign can be replaced with a plus sign if you change the sign of the number following it: 4 – 3 = 4 +(–3). The parentheses are used to show that the sign in front of the 3 is a negative sign and not a minus sign.

Examples

–82 – 14 = –82 +(–14)   20 –(–6) = 20 + 6   x – y = x +(–y)

Rewriting a Subtraction Problem as an Addition Problem Practice Problems

Practice

Rewrite as an addition problem.

1. 8 – 5

2. – 29 – 4

3. – 6 – (–10)

4. 15 – x

5. 40 – 85

6. y – 37

7. – x –(–14)

8. –x – 9

Solutions

1. 8 – 5 = 8 +(–5)

2. –29 – 4 = –29 +(–4)

3. –6 – (–10) = –6 + 10

4. 15 – x = 15 +(–x)

5. 40 – 85 = 40 +(–85)

6. y – 37 = y +(–37)

7. –x –(–14) = –x + 14

8. –x – 9 = – x +(–9)

Practice problems for this concept can be found at: Algebra: Negative Numbers Test.

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