Решение:
1. Умножение дробей:
- \( \frac{3}{4} \times \frac{2}{9} = \frac{3 \times 2}{4 \times 9} = \frac{6}{36} = \frac{1}{6} \)
- \( \frac{7}{5} \times \frac{15}{4} = \frac{7 \times 15}{5 \times 4} = \frac{7 \times 3}{1 \times 4} = \frac{21}{4} \)
- \( \frac{42}{53} \times \frac{1}{7} = \frac{42 \times 1}{53 \times 7} = \frac{6 \times 1}{53 \times 1} = \frac{6}{53} \)
- \( \frac{8}{15} \times \frac{25}{28} = \frac{8 \times 25}{15 \times 28} = \frac{2 \times 5}{3 \times 7} = \frac{10}{21} \)
- \( \frac{16}{35} \times \frac{7}{64} = \frac{16 \times 7}{35 \times 64} = \frac{1 \times 1}{5 \times 4} = \frac{1}{20} \)
Ответ: \( \frac{1}{6}, \frac{21}{4}, \frac{6}{53}, \frac{10}{21}, \frac{1}{20} \).