Найдите корень уравнения: б)y+y-4=;

Найдем корень уравнения:

$$\frac{5}{7}y + \frac{2}{3}y - 4 = \frac{1}{7}$$

$$\frac{15}{21}y + \frac{14}{21}y = \frac{1}{7} + 4$$

$$\frac{29}{21}y = \frac{1}{7} + \frac{28}{7}$$

$$\frac{29}{21}y = \frac{29}{7}$$

$$y = \frac{29}{7} : \frac{29}{21}$$

$$y = \frac{29}{7} \cdot \frac{21}{29} = 3$$

Ответ: 3