Вариант 2 1. Выполните действие: a) 7 16 8 21 8 4 6) 125 111 5 17 B) 17118 г) 5.315.

a) $$\frac{7}{8} \cdot \frac{16}{21} = \frac{7 \cdot 16}{8 \cdot 21} = \frac{7 \cdot 8 \cdot 2}{8 \cdot 7 \cdot 3} = \frac{2}{3}$$ 6) $$1\frac{8}{25} \cdot 1\frac{4}{11} = \frac{33}{25} \cdot \frac{15}{11} = \frac{33 \cdot 15}{25 \cdot 11} = \frac{11 \cdot 3 \cdot 5 \cdot 3}{5 \cdot 5 \cdot 11} = \frac{9}{5} = 1\frac{4}{5}$$ B) $$17\frac{5}{17} : 1\frac{7}{18} = \frac{294}{17} : \frac{25}{18} = \frac{294}{17} \cdot \frac{25}{18} = \frac{294 \cdot 25}{17 \cdot 18} = \frac{49 \cdot 6 \cdot 25}{17 \cdot 3 \cdot 6} = \frac{49 \cdot 25}{17 \cdot 3} = \frac{1225}{51} = 24\frac{1}{51}$$ г) $$5 : 3\frac{7}{15} = 5 : \frac{52}{15} = 5 \cdot \frac{15}{52} = \frac{5 \cdot 15}{52} = \frac{75}{52} = 1\frac{23}{52}$$ Ответ: а) $$\frac{2}{3}$$; б) $$1\frac{4}{5}$$; в) $$24\frac{1}{51}$$; г) $$1\frac{23}{52}$$