3. Решите уравнения: a) 7x + 10 = 5x + 2 б) 2(7 + 9x) = 6x + 2 в) $$x : \frac{1}{31} = 7\frac{3}{4} : \frac{1}{3}$$

a) $$7x + 10 = 5x + 2$$ $$7x - 5x = 2 - 10$$ $$2x = -8$$ $$x = -4$$ б) $$2(7 + 9x) = 6x + 2$$ $$14 + 18x = 6x + 2$$ $$18x - 6x = 2 - 14$$ $$12x = -12$$ $$x = -1$$ в) $$x : \frac{1}{31} = 7\frac{3}{4} : \frac{1}{3}$$ $$x * 31 = \frac{31}{4} * 3$$ $$x * 31 = \frac{93}{4}$$ $$x = \frac{93}{4} : 31$$ $$x = \frac{93}{4} * \frac{1}{31}$$ $$x = \frac{3}{4}$$ Ответ: a) x = -4; б) x = -1; в) $$x = \frac{3}{4}$$