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

а) $$(z - 6) \cdot \frac{3}{7} = 3$$ $$z - 6 = 3 : \frac{3}{7}$$ $$z - 6 = 3 \cdot \frac{7}{3}$$ $$z - 6 = 7$$ $$z = 7 + 6$$ $$z = 13$$ Ответ: z = 13 б) $$5\frac{1}{4} y - 5 = 5\frac{1}{4}$$ $$\frac{21}{4} y = \frac{21}{4} + 5$$ $$\frac{21}{4} y = \frac{21}{4} + \frac{20}{4}$$ $$\frac{21}{4} y = \frac{41}{4}$$ $$y = \frac{41}{4} : \frac{21}{4}$$ $$y = \frac{41}{4} \cdot \frac{4}{21}$$ $$y = \frac{41}{21} = 1\frac{20}{21}$$ Ответ: $$y = 1\frac{20}{21}$$