Вычислите: а) \(\left(\frac{7}{30}+\frac{1}{2}+\frac{4}{15}\right)\cdot\left(\frac{49}{50}-\frac{14}{25}-\frac{2}{5}\right)\); б) \(39:\left(\frac{3}{8}+\frac{1}{6}\right)+\left(\frac{3}{10}\right)^2\cdot\left(\frac{2}{3}-\frac{7}{18}\right)\).

1. а) \(\left(\frac{7}{30}+\frac{15}{30}+\frac{8}{30}\right)\cdot\left(\frac{49}{50}-\frac{28}{50}-\frac{20}{50}\right)=1\cdot\frac{1}{50}=\frac{1}{50}\).
2. б) \(39:\frac{13}{24}+\frac{9}{100}\cdot\frac{5}{18}=72+\frac{1}{40}=\frac{2881}{40}\).

Ответ: а) \(\frac{1}{50}\); б) \(\frac{2881}{40}\).