Subtraction equations

2-6 Subtraction Equations

Course 1Course 1

2-6 Subtraction Equations

Course 1

Warm UpWarm Up

Lesson PresentationLesson Presentation

Problem of the DayProblem of the Day

2-6 Subtraction Equations

Course 1

Warm UpSolve each equation.

1. x + 7 = 22

2. 18 + x = 105

3. 16 = x + 9

4. 23 = x + 4

x = 15

x = 87

x = 7

x = 19

2-6 Subtraction Equations

Course 1

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

2-6 Subtraction Equations

Course 1

Learn to solve whole-number subtraction equations.

2-6 Subtraction Equations

Course 1

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?

2-6 Subtraction Equations

Course 1

Abraham Lincoln’s age

John F. Kennedy’s age– = 8

Let a represent Abraham Lincoln’s age.

a – =8 43

a – 8 = 43

+ 8 + 8

a = 51

Abraham Lincoln was 51 years old when he became president.

2-6 Subtraction Equations

Course 1

y – 23 = 39 23 is subtracted from y.

+ 23

y = 62

Add 23 to both sides to undo the subtraction.

Check y – 23 = 39Substitute 62 for y in the equation.

Solve y – 23 = 39. Check your answer.

62 is the solution.39 = 39?

Additional Example 1A: Solving Subtraction Equations

62 – 23 = 39?

+ 23

2-6 Subtraction Equations

Course 1

78 = s – 15 15 is subtracted from s.+ 15

93 = s

Add 15 to both sides to undo the subtraction.

Check 78 = s – 15

Substitute 93 for s in the equation.

Solve 78 = s – 15. Check your answer.

93 is the solution.78 = 78?

Additional Example 1B: Solving Subtraction Equations

78 = 93 – 15?

+ 15

2-6 Subtraction Equations

Course 1

z – 3 = 12 3 is subtracted from z.+ 3

z = 15

Add 3 to both sides to undo the subtraction.

Check z – 3 = 12

Substitute 15 for z in the equation.

Solve z – 3 = 12. Check your answer.

15 is the solution.12 = 12?

Additional Example 1C: Solving Subtraction Equations

15 – 3 = 12?

+ 3

2-6 Subtraction Equations

Course 1

a – 4 = 7 4 is subtracted from a.+ 4

a = 11

Add 4 to both sides to undo the subtraction.

Check a – 4 = 7

Substitute 11 for a in the equation.

Solve a – 4 = 7. Check your answer.

11 is the solution.7 = 7?

11 – 4 = 7?

+ 4

Check It Out: Example 1A

2-6 Subtraction Equations

Course 1

57 = c – 13 13 is subtracted from c.

+ 13

70 = c

Add 13 to both sides to undo the subtraction.

Check 57 = c – 13

Substitute 70 for c in the equation.

Solve 57 = c – 13. Check your answer.

70 is the solution.57 = 57?

57 = 70 – 13?

+ 13

Check It Out: Example 1B

2-6 Subtraction Equations

Course 1

g – 62 = 14 62 is subtracted from g.

+ 62

g = 76

Add 62 to both sides to undo the subtraction.

Check g – 62 = 14

Substitute 76 for g in the equation.

Solve g – 62 = 14. Check your answer.

76 is the solution.14 = 14?

76 – 62 = 14?

+ 62

Check It Out: Example 1C

2-6 Subtraction Equations

Course 1

1. x – 9 = 21

2. 14 = x – 3

3. x – 7 = 11

4. 16 = x – 14

5. x – 9 = 11

Lesson Quiz

6. Susan is taller than James. The difference in their height is 4 inches. James is 62 inches tall. How tall is Susan?

x = 30

x = 17

x = 18

x = 30

x = 20

66 inches