Найдите значение выражения: а) \(\frac{6}{5} : (\frac{9}{10} - \frac{1}{5})\); б) \((\frac{7}{25} + \frac{1}{5}) : \frac{3}{50}\); в) \(1 - \frac{3}{7} : \frac{15}{28}\); г) \(\frac{34}{9} : \frac{17}{54} \cdot \frac{5}{6}\).

1. \(\frac{6}{5} : (\frac{9}{10}-\frac{1}{5})=\frac{6}{5}:\frac{7}{10}=\frac{6}{5}\cdot\frac{10}{7}=\frac{12}{7}\).
2. \((\frac{7}{25}+\frac{1}{5}):\frac{3}{50}=(\frac{7}{25}+\frac{5}{25}):\frac{3}{50}=\frac{12}{25}\cdot\frac{50}{3}=8\).
3. \(1-\frac{3}{7}:\frac{15}{28}=1-\frac{3}{7}\cdot\frac{28}{15}=1-\frac{4}{5}=\frac{1}{5}\).
4. \(\frac{34}{9}:\frac{17}{54}\cdot\frac{5}{6}=\frac{34}{9}\cdot\frac{54}{17}\cdot\frac{5}{6}=20\).

Ответ: а) \(\frac{12}{7}\); б) \(8\); в) \(\frac{1}{5}\); г) \(20\).