Chapter 3 - Solving Inequalities - 3-6 Compound Inequalities - Practice and Problem-Solving Exercises - Page 206: 52

a) $ 102.5 \leq R \leq 184.5$ b) 22 years old

a) $0.5*(220-a) \leq R \leq 0.9*(220-a)$ $0.5*(220-15) \leq R \leq 0.9*(220-15)$ $0.5 * 205 \leq R \leq 0.9 * 205 $ $ 102.5 \leq R \leq 184.5$ b) $99 = 0.5 * (220-a)$ $99 * 2 = 2 * 0.5 * (220-a)$ $198 = 220 - a $ $198 - 198 + a = 220 - 198 - a + a$ $a = 22 $ $x = 0.9 * (220 - 22)$ $x = 0.9 * 198 $ $x = 178.2$