8 : 7 = x: 56 a 0,6 = 17 12 7-y 6 = 5 9 9 : 2 13 36 = 27 85 1 4

Решение:

1. 8 : 7 = x : 56 $$\frac{8}{7} = \frac{x}{56}$$ $$x = \frac{8 \cdot 56}{7}$$ $$x = \frac{8 \cdot 8 \cdot 7}{7}$$ $$x = 8 \cdot 8$$ $$x = 64$$
2. $$\frac{a}{0.6} = \frac{17}{12}$$ $$a = \frac{17 \cdot 0.6}{12}$$ $$a = \frac{17 \cdot 6}{12 \cdot 10}$$ $$a = \frac{17}{2 \cdot 10}$$ $$a = \frac{17}{20}$$ $$a = 0.85$$
3. $$\frac{7 - y}{6} = \frac{5}{9}$$ $$7 - y = \frac{5 \cdot 6}{9}$$ $$7 - y = \frac{5 \cdot 2 \cdot 3}{3 \cdot 3}$$ $$7 - y = \frac{10}{3}$$ $$y = 7 - \frac{10}{3}$$ $$y = \frac{21}{3} - \frac{10}{3}$$ $$y = \frac{11}{3}$$ $$y = 3 \frac{2}{3}$$
4. $$9 : 2 \frac{13}{36} = \frac{27}{85} : \frac{1}{4}$$ $$\frac{9}{\frac{2 \cdot 36 + 13}{36}} = \frac{27}{85} : \frac{1}{4}$$ $$\frac{9}{\frac{72 + 13}{36}} = \frac{27}{85} : \frac{1}{4}$$ $$\frac{9}{\frac{85}{36}} = \frac{27}{85} : \frac{1}{4}$$ $$\frac{9 \cdot 36}{85} = \frac{27}{85} : \frac{1}{4}$$ $$\frac{324}{85} = \frac{27 \cdot 4}{85}$$ $$\frac{324}{85} = \frac{108}{85}$$

Проверка:

$$\frac{324}{85}
e \frac{108}{85}$$

Равенство неверно

Ответ: 1) x = 64; 2) a = 0.85; 3) $$y = 3 \frac{2}{3}$$; 4) Равенство неверно