1 Вычислите: a) 7.\frac{3}{28}; б) \frac{5}{8} \cdot \frac{4}{5}; в) \frac{5}{8} \cdot 24; г) 200 \cdot \frac{26}{4000} \cdot \frac{2}{13}

a) 7$$\cdot \frac{3}{28}$$ = $$\frac{7}{1} \cdot \frac{3}{28}$$ = $$\frac{7 \cdot 3}{1 \cdot 28}$$ = $$\frac{21}{28}$$ = $$\frac{3}{4}

б) $$\frac{5}{8} \cdot \frac{4}{5}$$ = $$\frac{5 \cdot 4}{8 \cdot 5}$$ = $$\frac{20}{40}$$ = $$\frac{1}{2}

в) $$\frac{5}{8} \cdot 24$$ = $$\frac{5}{8} \cdot \frac{24}{1}$$ = $$\frac{5 \cdot 24}{8 \cdot 1}$$ = $$\frac{120}{8}$$ = 15

г) 200$$\cdot \frac{26}{4000} \cdot \frac{2}{13}$$ = $$\frac{200}{1} \cdot \frac{26}{4000} \cdot \frac{2}{13}$$ = $$\frac{200 \cdot 26 \cdot 2}{1 \cdot 4000 \cdot 13}$$ = $$\frac{10400}{52000}$$ = $$\frac{1}{5}

Ответ: а) $$\frac{3}{4}$$; б) $$\frac{1}{2}$$; в) 15; г) $$\frac{1}{5}$$