Ответ:

  1. а) \(\frac{5}{8}\cdot\frac{12}{25}=\frac{3}{10}\).
  2. б) \(\frac{9}{14}\cdot\frac{3}{7}=\frac{27}{98}\).
  3. в) \(\frac{7}{9}\cdot\frac{15}{28}=\frac{5}{12}\).
  4. г) \(\frac{8}{15}:\frac{4}{9}=\frac{8}{15}\cdot\frac{9}{4}=\frac{6}{5}\).

Ответ: а) \(\frac{3}{10}\); б) \(\frac{27}{98}\); в) \(\frac{5}{12}\); г) \(\frac{6}{5}\).