4. Найдите: a) \(\frac{9}{10}\) от \(\frac{2}{3}\) b) \(\frac{3}{16}\) от \(\frac{4}{9}\) c) \(\frac{3}{5}\) от \(\frac{5}{12}\) d) \(\frac{3}{4}\) от \(\frac{8}{15}\) e) \(\frac{4}{5}\) от \(\frac{3}{8}\) f) \(\frac{5}{7}\) от \(\frac{14}{25}\)

Решение: a) \(\frac{9}{10}\) от \(\frac{2}{3}\) = \(\frac{9}{10} \cdot \frac{2}{3} = \frac{9 \cdot 2}{10 \cdot 3} = \frac{18}{30} = \frac{3}{5}\). Ответ: \(\frac{3}{5}\) b) \(\frac{3}{16}\) от \(\frac{4}{9}\) = \(\frac{3}{16} \cdot \frac{4}{9} = \frac{3 \cdot 4}{16 \cdot 9} = \frac{12}{144} = \frac{1}{12}\). Ответ: \(\frac{1}{12}\) c) \(\frac{3}{5}\) от \(\frac{5}{12}\) = \(\frac{3}{5} \cdot \frac{5}{12} = \frac{3 \cdot 5}{5 \cdot 12} = \frac{15}{60} = \frac{1}{4}\). Ответ: \(\frac{1}{4}\) d) \(\frac{3}{4}\) от \(\frac{8}{15}\) = \(\frac{3}{4} \cdot \frac{8}{15} = \frac{3 \cdot 8}{4 \cdot 15} = \frac{24}{60} = \frac{2}{5}\). Ответ: \(\frac{2}{5}\) e) \(\frac{4}{5}\) от \(\frac{3}{8}\) = \(\frac{4}{5} \cdot \frac{3}{8} = \frac{4 \cdot 3}{5 \cdot 8} = \frac{12}{40} = \frac{3}{10}\). Ответ: \(\frac{3}{10}\) f) \(\frac{5}{7}\) от \(\frac{14}{25}\) = \(\frac{5}{7} \cdot \frac{14}{25} = \frac{5 \cdot 14}{7 \cdot 25} = \frac{70}{175} = \frac{2}{5}\). Ответ: \(\frac{2}{5}\)