Вычислите: а) \(\frac{1}{2}+\frac{1}{7}+\frac{1}{5}\); б) \(\frac{5}{7}-\frac{3}{28}-\frac{1}{4}\).

1. \(\frac{1}{2}+\frac{1}{7}+\frac{1}{5}=\frac{35}{70}+\frac{10}{70}+\frac{14}{70}=\frac{59}{70}\).
2. \(\frac{5}{7}-\frac{3}{28}-\frac{1}{4}=\frac{20}{28}-\frac{3}{28}-\frac{7}{28}=\frac{10}{28}=\frac{5}{14}\).

Ответ: а) \(\frac{59}{70}\); б) \(\frac{5}{14}\).