L9 · Subtraction with negative integers

1. 1.

   Rewrite 7 − (−3) as addition, then evaluate.

   Answer. 10

   Subtracting −3 is adding 3: 7 + 3 = 10.

2. 2.

   Rewrite 6 − (−6) as addition, then evaluate.

   Answer. 12

   Subtracting −6 is adding 6: 6 + 6 = 12.

3. 3.

   Rewrite 1 − (−7) as addition, then evaluate.

   Answer. 8

   Subtracting −7 is adding 7: 1 + 7 = 8.

4. 4.

   Rewrite 3 − (−2) as addition, then evaluate.

   Answer. 5

   Subtracting −2 is adding 2: 3 + 2 = 5.

5. 5.

   Rewrite 1 − (−7) as addition, then evaluate. Then Grace needs 4 of that amount. What is the total they need?

   Answer. 32

   Subtracting −7 is adding 7: 1 + 7 = 8. Then multiply by 4: 32.

6. 6.

   Rewrite 4 − (−1) as addition, then evaluate. Then Mei needs 2 of that amount. What is the total they need?

   Answer. 10

   Subtracting −1 is adding 1: 4 + 1 = 5. Then multiply by 2: 10.

7. 7.

   Rewrite 7 − (−7) as addition, then evaluate. Then Priya needs 5 of that amount. What is the total they need?

   Answer. 70

   Subtracting −7 is adding 7: 7 + 7 = 14. Then multiply by 5: 70.

8. 8.

   Rewrite 5 − (−4) as addition, then evaluate. Then Ava needs 5 of that amount. What is the total they need?

   Answer. 45

   Subtracting −4 is adding 4: 5 + 4 = 9. Then multiply by 5: 45.

9. 9.

   Rewrite 4 − (−5) as addition, then evaluate. Then Sam needs 4 of that amount. What is the total they need?

   Answer. 36

   Subtracting −5 is adding 5: 4 + 5 = 9. Then multiply by 4: 36.

10. 10.

    Rewrite 2 − (−7) as addition, then evaluate. Then Owen needs 3 of that amount. What is the total they need?

    Answer. 27

    Subtracting −7 is adding 7: 2 + 7 = 9. Then multiply by 3: 27.

11. 11.

    Think

    Sam tried this problem:
    Rewrite 1 − (−8) as addition, then evaluate.
    Sam wrote 10. That is not correct. What is the right answer?

    Answer. 9

    Sam’s answer 10 is off. Subtracting −8 is adding 8: 1 + 8 = 9.

12. 12.

    Think

    Mei tried this problem:
    Rewrite 2 − (−6) as addition, then evaluate.
    Mei wrote 16. That is not correct. What is the right answer?

    Answer. 8

    Mei’s answer 16 is off. Subtracting −6 is adding 6: 2 + 6 = 8.

Original extra practice. Keys are computed from the items, not guessed.