4. Решить уравнение: a) 7:8=x:96; 6) y:1- =7-:-; в) x =25 5 3 1 4 3 0,6 3

a) $$7:8 = x:96$$

$$\frac{7}{8} = \frac{x}{96}$$

$$x = \frac{7 \times 96}{8} = 7 \times 12 = 84$$

б) $$y : 1\frac{5}{31} = 7\frac{3}{4} : \frac{1}{3}$$

Преобразуем смешанные дроби в неправильные: $$1\frac{5}{31} = \frac{1 \times 31 + 5}{31} = \frac{36}{31}$$ и $$7\frac{3}{4} = \frac{7 \times 4 + 3}{4} = \frac{31}{4}$$.

$$y : \frac{36}{31} = \frac{31}{4} : \frac{1}{3}$$

$$y : \frac{36}{31} = \frac{31}{4} \times 3$$

$$y : \frac{36}{31} = \frac{93}{4}$$

$$y = \frac{93}{4} \times \frac{36}{31} = \frac{93 \times 9}{31} = 3 \times 9 = 27$$

в) $$\frac{x}{0,6} = \frac{25}{3}$$

$$x = \frac{25 \times 0,6}{3} = \frac{25 \times 6}{3 \times 10} = \frac{25 \times 2}{10} = \frac{50}{10} = 5$$

Ответ: a) x = 84; б) y = 27; в) x = 5