Learn to solve whole-number subtraction equations .

1. Learn to solve whole-number subtraction equations.

2. When Theodore Roosevelt became president of the United States, he was 42 years old. He was 27 years younger than Ronald Reagan was when Reagan became president. How old was Reagan when he became president?

3. 27 + 27 + 27 Let a represent Ronald Reagan’s age. Ronald Reagan’s age Theodore Roosevelt’s age – = – = a 27 42 a – 27 = 42 a = 69 Ronald Reagan was 69 years old when he became president.

4. + 23 + 23 ? 62 – 23 = 39 ? 39 = 39 Additional Example 1A: Solving Subtraction Equations Solve y – 23 = 39. Check your answer. y – 23 = 39 23 is subtracted fromy. Add 23 to both sides to undo the subtraction. y = 62 Check y – 23 = 39 Substitute 62 fory in the equation. 62 is the solution. 

5. + 15 + 15 ? 78 =93 – 15 ? 78 = 78 Additional Example 1B: Solving Subtraction Equations Solve 78 = s – 15. Check your answer. 78 = s – 15 15 is subtracted froms. Add 15 to both sides to undo the subtraction. 93 = s Check 78=s – 15 Substitute 93 fors in the equation. 93 is the solution. 

6. + 3 + 3 ? 15 – 3 = 12 ? 12 = 12 Additional Example 1C: Solving Subtraction Equations Solve z – 3 = 12. Check your answer. 3 is subtracted fromz. z – 3 = 12 Add 3 to both sides to undo the subtraction. z = 15 Check z – 3 = 12 Substitute 15 forz in the equation. 15 is the solution. 

7. + 4 + 4 ? 11 – 4 = 7 ? 7 = 7 Check It Out: Example 1A Solve a – 4 = 7. Check your answer. a – 4 = 7 4 is subtracted froma. Add 4 to both sides to undo the subtraction. a = 11 Check a – 4 = 7 Substitute 11 fora in the equation. 11 is the solution. 

8. + 13 + 13 ? 57 =70 – 13 ? 57 = 57 Check It Out: Example 1B Solve 57 = c – 13. Check your answer. 57 = c – 13 13 is subtracted fromc. Add 13 to both sides to undo the subtraction. 70 = c Check 57=c – 13 Substitute 70 forc in the equation. 70 is the solution. 

9. + 62 + 62 ? 76 – 62 = 14 ? 14 = 14 Check It Out: Example 1C Solve g – 62 = 14. Check your answer. g – 62 = 14 62 is subtracted fromg. Add 62 to both sides to undo the subtraction. g = 76 Check g – 62 = 14 Substitute 76 forg in the equation. 76 is the solution. 