1. Subtraction Equations
2-6
Subtraction Equations
Warm Up
Problem of the Day
Lesson Presentation
Course 1
Course 1

2. Warm Up
Solve each equation.
1. x + 7 = 22
x = 105
3. 16 = x + 9
4. 23 = x + 4
x = 15
x = 87
x = 7
x = 19

3. Problem of the Day
Bruce has 25 CDs remaining after giving 14 to John, 17 to Mary, and 25 to Sue. How many CDs did he begin with? 81

4. Learn to solve whole-number subtraction equations.

5. When John F. Kennedy became president of the United States, he was 43 years old, which was 8 years younger than Abraham Lincoln was when Lincoln became President. How old was Lincoln when he became president?

6. Let a represent Abraham Lincoln’s age.8
John F. Kennedy’s age – = – = a 8 43
a – 8 = 43
+ 8
+ 8
a = 51
Abraham Lincoln was 51 years old when he became president.

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

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

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

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

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

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

13. Lesson Quiz
1. x – 9 = 21
2. 14 = x – 3
3. x – 7 = 11
4. 16 = x – 14
5. x – 9 = 11
x = 30
x = 17
x = 18
x = 30
x = 20
6. Susan is taller than James. The difference in their height is 4 inches. James is 62 inches tall. How tall is Susan?
66 inches