## Precalculus: Mathematics for Calculus, 7th Edition

(a) $\frac{17}{30}$ (b) $\frac{9}{20}$
(a) $\frac{3}{10}+\frac{4}{15}$ Least Common Denominator of 10 and 15 = 30 Therefore, $\frac{9}{30}+\frac{8}{30} = \frac{17}{30}$ (b) $\frac{1}{4}+\frac{1}{5}$ Least Common Denominator of 4 and 5 = 20 Therefore, $\frac{5}{20}+\frac{4}{20} = \frac{9}{20}$