1. Вычислите: a) $$\frac{5}{6} \cdot \frac{7}{9}$$ b) $$\frac{3}{5} \cdot 6$$ c) $$3 \frac{3}{8} : \frac{9}{16}$$ d) $$3 : \frac{9}{14}$$

Решение: a) $$\frac{5}{6} \cdot \frac{7}{9} = \frac{5 \cdot 7}{6 \cdot 9} = \frac{35}{54}$$ б) $$\frac{3}{5} \cdot 6 = \frac{3 \cdot 6}{5} = \frac{18}{5} = 3 \frac{3}{5}$$ в) $$3 \frac{3}{8} : \frac{9}{16} = \frac{3 \cdot 8 + 3}{8} : \frac{9}{16} = \frac{27}{8} : \frac{9}{16} = \frac{27}{8} \cdot \frac{16}{9} = \frac{27 \cdot 16}{8 \cdot 9} = \frac{3 \cdot 2}{1 \cdot 1} = 6$$ г) $$3 : \frac{9}{14} = \frac{3}{1} : \frac{9}{14} = \frac{3}{1} \cdot \frac{14}{9} = \frac{3 \cdot 14}{1 \cdot 9} = \frac{1 \cdot 14}{1 \cdot 3} = \frac{14}{3} = 4 \frac{2}{3}$$