Addition and Subtraction Worksheets with Answer Key - Free Printable

Let's solve each problem step by step, using the rules for adding and subtracting negative numbers.

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🔷 Rules to Remember:

1. Adding a negative number is the same as subtracting a positive number:
- $ a + (-b) = a - b $
2. Subtracting a negative number is the same as adding a positive number:
- $ a - (-b) = a + b $
3. When adding two negative numbers, add their absolute values and keep the negative sign.
4. When subtracting a positive number from a negative number, it becomes more negative.

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Now let's solve each one:

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1. $(-4) + (-5) = -4 - 5 = \boxed{-9}$
→ Adding two negatives → combine them: $-4 - 5 = -9$

2. $8 + (-12) = 8 - 12 = \boxed{-4}$
→ Adding a negative is like subtracting: $8 - 12 = -4$

3. $(-1) - 7 = -1 - 7 = \boxed{-8}$
→ Subtracting a positive makes it more negative

4. $(-18) - 20 = -18 - 20 = \boxed{-38}$
→ Two negatives: $-18 - 20 = -38$

5. $(-17) - 1 = -17 - 1 = \boxed{-18}$
→ Just subtract: $-17 - 1 = -18$

6. $13 - (-18) = 13 + 18 = \boxed{31}$
→ Subtracting a negative = adding: $13 + 18 = 31$

7. $(-9) + (-11) = -9 - 11 = \boxed{-20}$
→ Add the absolute values: $9 + 11 = 20$, keep negative

8. $1 + (-12) = 1 - 12 = \boxed{-11}$
→ Same as $1 - 12 = -11$

9. $(-8) - 2 = -8 - 2 = \boxed{-10}$
→ Subtracting positive → more negative

10. $0 - (-10) = 0 + 10 = \boxed{10}$
→ Subtracting a negative = adding: $0 + 10 = 10$

11. $38 - (-27) = 38 + 27 = \boxed{65}$
→ Subtracting a negative → add: $38 + 27 = 65$

12. $6 - (-38) = 6 + 38 = \boxed{44}$
→ Again, subtracting a negative = adding: $6 + 38 = 44$

13. $24 - (-31) = 24 + 31 = \boxed{55}$
→ $24 + 31 = 55$

14. $(-99) - 88 = -99 - 88 = \boxed{-187}$
→ Subtracting a positive from a negative → more negative: $-99 - 88 = -187$

15. $4 + (-9) = 4 - 9 = \boxed{-5}$
→ $4 - 9 = -5$

16. $(-1) + (-10) = -1 - 10 = \boxed{-11}$
→ Add the negatives: $-1 - 10 = -11$

17. $50 - (-10) = 50 + 10 = \boxed{60}$
→ Subtracting a negative → add: $50 + 10 = 60$

18. $(-60) - 12 = -60 - 12 = \boxed{-72}$
→ Subtracting a positive from a negative → more negative

19. $(-9) - (-19) = -9 + 19 = \boxed{10}$
→ Subtracting a negative → add: $-9 + 19 = 10$

20. $(-11) + (-10) = -11 - 10 = \boxed{-21}$
→ Two negatives added: $-11 - 10 = -21$

21. $49 - (-40) = 49 + 40 = \boxed{89}$
→ Subtracting a negative → add: $49 + 40 = 89$

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✔ Final Answers:

| Problem | Answer |
|--------|--------|
| 1 | -9 |
| 2 | -4 |
| 3 | -8 |
| 4 | -38 |
| 5 | -18 |
| 6 | 31 |
| 7 | -20 |
| 8 | -11 |
| 9 | -10 |
| 10 | 10 |
| 11 | 65 |
| 12 | 44 |
| 13 | 55 |
| 14 | -187 |
| 15 | -5 |
| 16 | -11 |
| 17 | 60 |
| 18 | -72 |
| 19 | 10 |
| 20 | -21 |
| 21 | 89 |

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✔ All problems solved! Let me know if you'd like this printed or formatted differently.