1.38. Решите уравнения: a) 3x - 6 = x + 4; б) x + (x – 20) + 3x = 180;

a) $$3x - 6 = x + 4$$ $$3x - x = 4 + 6$$ $$2x = 10$$ $$x = \frac{10}{2}$$ $$\mathbf{x = 5}$$ б) $$x + (x - 20) + 3x = 180$$ $$x + x - 20 + 3x = 180$$ $$5x = 180 + 20$$ $$5x = 200$$ $$x = \frac{200}{5}$$ $$\mathbf{x = 40}$$