14. \(\frac{14}{21}\cdot\frac{15}{28}=\)

Сократим: \(\frac{14}{28}=\frac{1}{2}\), \(\frac{15}{21}=\frac{5}{7}\).

\(\frac{14}{21}\cdot\frac{15}{28}=\frac{1}{2}\cdot\frac{5}{7}=\frac{5}{14}\).

Ответ: \(\frac{5}{14}\)