Решите уравнение: 1) 7 : 8 = x : 96; 2) y : 1$$\frac{5}{31}$$ = 7$$\frac{3}{4}$$ : $$\frac{4}{9}$$; 3) $$\frac{a}{0,6} = \frac{25}{3}$$; 4) $$\frac{2+x}{5} = \frac{4}{9}$$.

Решим каждое уравнение по отдельности:

1. $$7 : 8 = x : 96$$

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

   $$x = \frac{7 \cdot 96}{8} = \frac{7 \cdot 12}{1} = 84$$

   Ответ: x = 84.

2. y : 1$$\frac{5}{31}$$ = 7$$\frac{3}{4}$$ : $$\frac{4}{9}$$

   $$y : \frac{36}{31} = \frac{31}{4} : \frac{4}{9}$$

   $$y : \frac{36}{31} = \frac{31}{4} \cdot \frac{9}{4}$$

   $$y : \frac{36}{31} = \frac{279}{16}$$

   $$y = \frac{279}{16} \cdot \frac{36}{31} = \frac{279 \cdot 9}{4 \cdot 31} = \frac{2511}{124}$$

   $$y = 20 \frac{31}{124} = 20 \frac{1}{4}$$

   Ответ: y = 20$$\frac{31}{124}$$.

3. $$\frac{a}{0,6} = \frac{25}{3}$$

   $$a = \frac{25 \cdot 0,6}{3} = \frac{25 \cdot 6}{3 \cdot 10} = \frac{25 \cdot 2}{10} = \frac{50}{10} = 5$$

   Ответ: a = 5.

4. $$\frac{2+x}{5} = \frac{4}{9}$$

   $$2+x = \frac{4 \cdot 5}{9} = \frac{20}{9}$$

   $$x = \frac{20}{9} - 2 = \frac{20}{9} - \frac{18}{9} = \frac{2}{9}$$

   Ответ: x = $$\frac{2}{9}$$.