2.464 Решите уравнение: a) (z - 6) * 1/4 = 3/7; б) 5 1/4 - 5 * y = 5/4;

a) $$(z - 6) \cdot \frac{1}{4} = \frac{3}{7}$$

$$z - 6 = \frac{3}{7} : \frac{1}{4}$$

$$z - 6 = \frac{3}{7} \cdot 4$$

$$z - 6 = \frac{12}{7}$$

$$z = \frac{12}{7} + 6$$

$$z = \frac{12}{7} + \frac{42}{7}$$

$$z = \frac{54}{7} = 7\frac{5}{7}$$

б) $$5\frac{1}{4} - 5y = \frac{5}{4}$$

$$\frac{21}{4} - 5y = \frac{5}{4}$$

$$5y = \frac{21}{4} - \frac{5}{4}$$

$$5y = \frac{16}{4}$$

$$5y = 4$$

$$y = \frac{4}{5}$$

Ответ: а) $$z=7\frac{5}{7}$$; б) $$y=\frac{4}{5}$$.