3. Выполните действия: a) $$1 \frac{7}{9} : 2 \frac{2}{3}$$; б) $$3 \frac{3}{5} : 2 \frac{1}{10}$$; в) $$8 \frac{3}{8} : \frac{3}{14} \cdot 7$$;

a) $$1 \frac{7}{9} : 2 \frac{2}{3} = \frac{16}{9} : \frac{8}{3} = \frac{16}{9} \cdot \frac{3}{8} = \frac{16 \cdot 3}{9 \cdot 8} = \frac{2 \cdot 1}{3 \cdot 1} = \frac{2}{3}$$ б) $$3 \frac{3}{5} : 2 \frac{1}{10} = \frac{18}{5} : \frac{21}{10} = \frac{18}{5} \cdot \frac{10}{21} = \frac{18 \cdot 10}{5 \cdot 21} = \frac{6 \cdot 2}{1 \cdot 7} = \frac{12}{7} = 1 \frac{5}{7}$$ в) $$8 \frac{3}{8} : \frac{5}{6} \cdot (-\frac{12}{25})$$ \qquad -2 \frac{2}{3} \cdot (-2 \frac{1}{4}) = \frac{67}{8} \cdot \frac{14}{5} = \frac{67 \cdot 14}{8 \cdot 5} = \frac{67 \cdot 7}{4 \cdot 5} = \frac{469}{20} = 23 \frac{9}{20}$$