Ответ:

  1. \(\frac{6}{25}\cdot\frac{10}{9}=\frac{4}{15}\).
  2. \(\frac{14}{15}\cdot\frac{5}{21}=\frac{2}{9}\).
  3. \(\frac{8}{27}\cdot\frac{9}{16}=\frac{1}{6}\).
  4. \(\frac{12}{35}\cdot\frac{7}{18}=\frac{2}{15}\).
  5. \(\frac{15}{28}\cdot\frac{14}{25}=\frac{3}{10}\).