Solve the inequality

4 ≤ 2c +7 ≤ 21

4 < = 2 c + 7 < = 21 Subbtract 7

4 - 7 < = 2 c + 7 - 7 < = 21 - 7

- 3 < = 2 c < = 14 Divide by 2

- 3 / 2 < = 2 c / 2 < = 14 / 2

- 3 / 2 < = c < = 7