1. Выполните деление: 1) $$\frac{5}{7} : \frac{4}{5}$$; 2) $$\frac{6}{35} : \frac{18}{49}$$; 3) $$\frac{27}{28} : \frac{9}{56}$$; 4) $$\frac{28}{45} : \frac{63}{40}$$

Решение: 1) $$\frac{5}{7} : \frac{4}{5} = \frac{5}{7} \cdot \frac{5}{4} = \frac{25}{28}$$ 2) $$\frac{6}{35} : \frac{18}{49} = \frac{6}{35} \cdot \frac{49}{18} = \frac{6 \cdot 49}{35 \cdot 18} = \frac{6 \cdot 7 \cdot 7}{5 \cdot 7 \cdot 6 \cdot 3} = \frac{7}{5 \cdot 3} = \frac{7}{15}$$ 3) $$\frac{27}{28} : \frac{9}{56} = \frac{27}{28} \cdot \frac{56}{9} = \frac{27 \cdot 56}{28 \cdot 9} = \frac{3 \cdot 9 \cdot 2 \cdot 28}{28 \cdot 9} = 3 \cdot 2 = 6$$ 4) $$\frac{28}{45} : \frac{63}{40} = \frac{28}{45} \cdot \frac{40}{63} = \frac{28 \cdot 40}{45 \cdot 63} = \frac{4 \cdot 7 \cdot 8 \cdot 5}{9 \cdot 5 \cdot 9 \cdot 7} = \frac{4 \cdot 8}{9 \cdot 9} = \frac{32}{81}$$ Ответы: 1) $$\frac{25}{28}$$; 2) $$\frac{7}{15}$$; 3) $$6$$; 4) $$\frac{32}{81}$$