а) \(\frac{3}{5} \cdot \frac{2}{7} = \frac{3 \cdot 2}{5 \cdot 7} = \frac{6}{35}\)
б) \(\frac{4}{15} \cdot \frac{3}{16} = \frac{4 \cdot 3}{15 \cdot 16} = \frac{12}{240} = \frac{1}{20}\)
в) \(\frac{3}{7} \cdot \frac{5}{8} = \frac{3 \cdot 5}{7 \cdot 8} = \frac{15}{56}\)
г) \(\frac{2}{3} \cdot \frac{2}{7} = \frac{2 \cdot 2}{3 \cdot 7} = \frac{4}{21}\)
Ответ: а) \(\frac{6}{35}\), б) \(\frac{1}{20}\), в) \(\frac{15}{56}\), г) \(\frac{4}{21}\).