Вычислите: $\frac{35}{24} : \frac{15}{32} - 3$

18. $$ \frac{35}{24} : \frac{15}{32} - 3 = \frac{35}{24} \cdot \frac{32}{15} - 3 = \frac{7 \cdot 5}{3 \cdot 8} \cdot \frac{4 \cdot 8}{3 \cdot 5} - 3 = \frac{7 \cdot 4}{3 \cdot 3} - 3 = \frac{28}{9} - 3 = \frac{28}{9} - \frac{27}{9} = \frac{1}{9} $$ **Ответ:** $\frac{1}{9}$ 19. $$ 2 - \frac{15}{28} : \frac{10}{21} = 2 - \frac{15}{28} \cdot \frac{21}{10} = 2 - \frac{3 \cdot 5}{4 \cdot 7} \cdot \frac{3 \cdot 7}{2 \cdot 5} = 2 - \frac{3 \cdot 3}{4 \cdot 2} = 2 - \frac{9}{8} = \frac{16}{8} - \frac{9}{8} = \frac{7}{8} $$ **Ответ:** $\frac{7}{8}$ 20. $$ 18 \cdot \frac{5}{81} - \frac{2}{3} = \frac{18 \cdot 5}{81} - \frac{2}{3} = \frac{2 \cdot 9 \cdot 5}{9 \cdot 9} - \frac{2}{3} = \frac{2 \cdot 5}{9} - \frac{2}{3} = \frac{10}{9} - \frac{6}{9} = \frac{4}{9} $$ **Ответ:** $\frac{4}{9}$ 21. $$ 24 \cdot \frac{3}{64} - \frac{3}{4} = \frac{24 \cdot 3}{64} - \frac{3}{4} = \frac{3 \cdot 8 \cdot 3}{8 \cdot 8} - \frac{3}{4} = \frac{9}{8} - \frac{3}{4} = \frac{9}{8} - \frac{6}{8} = \frac{3}{8} $$ **Ответ:** $\frac{3}{8}$ 22. $$ \frac{18}{35} : \left( 12 + \frac{1}{10} \right) = \frac{18}{35} : \left( \frac{120}{10} + \frac{1}{10} \right) = \frac{18}{35} : \frac{121}{10} = \frac{18}{35} \cdot \frac{10}{121} = \frac{18 \cdot (2 \cdot 5)}{ (7 \cdot 5) \cdot 121} = \frac{18 \cdot 2}{7 \cdot 121} = \frac{36}{847} $$ **Ответ:** $\frac{36}{847}$