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

• а) $$(z - 6) \cdot \frac{3}{7} = 3$$

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

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

$$z - 6 = 7$$

$$z = 7 + 6$$

$$z = 13$$

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

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

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

$$\frac{21}{4}y = \frac{26}{4}$$

$$y = \frac{26}{4} : \frac{21}{4}$$

$$y = \frac{26}{4} \cdot \frac{4}{21}$$

$$y = \frac{26}{21} = 1\frac{5}{21}$$

Ответ: а) 13; б) $$1\frac{5}{21}$$