642. Решите уравнение: a) (x – 8) * 2/5 = 2; б) 2 1/3 x – 2 1/3 = 2 1/3.

642. Решите уравнение:

1. a) $$(x - 8) \cdot \frac{2}{5} = 2;$$$$x - 8 = 2 : \frac{2}{5};$$$$x - 8 = 2 \cdot \frac{5}{2};$$$$x - 8 = \frac{2 \cdot 5}{2};$$$$x - 8 = 5;$$$$x = 5 + 8;$$$$x = 13;$$
2. б) $$2 \frac{1}{3}x - 2 \frac{1}{3} = 2 \frac{1}{3};$$$$\frac{7}{3}x - \frac{7}{3} = \frac{7}{3};$$$$\frac{7}{3}x = \frac{7}{3} + \frac{7}{3};$$$$\frac{7}{3}x = \frac{14}{3};$$$$x = \frac{14}{3} : \frac{7}{3};$$$$x = \frac{14}{3} \cdot \frac{3}{7};$$$$x = \frac{14 \cdot 3}{3 \cdot 7};$$$$x = 2.$$

Ответ: a) $$x = 13$$; б) $$x = 2$$.