1. a) \(\frac{4}{7} \cdot \frac{21}{32} = \frac{4 \cdot 21}{7 \cdot 32} = \frac{1 \cdot 3}{1 \cdot 8} = \frac{3}{8}\)
б) \(\frac{3}{6} \cdot \frac{8}{9} = \frac{3 \cdot 8}{6 \cdot 9} = \frac{1 \cdot 4}{3 \cdot 3} = \frac{4}{9}\)
в) \(\frac{5}{11} \cdot \frac{4}{15} = \frac{5 \cdot 4}{11 \cdot 15} = \frac{1 \cdot 4}{11 \cdot 3} = \frac{4}{33}\)
г) \(\frac{9}{14} \cdot \frac{5}{12} = \frac{9 \cdot 5}{14 \cdot 12} = \frac{3 \cdot 5}{14 \cdot 4} = \frac{15}{56}\)