Решите уравнение: 1) $$2x = 18 - x$$; 2) $$7x + 3 = 30 - 2x$$; 3) $$7 - 2x = 3x - 18$$

Решение: 1) $$2x = 18 - x \Rightarrow 2x + x = 18 \Rightarrow 3x = 18 \Rightarrow x = \frac{18}{3} \Rightarrow x = 6$$ 2) $$7x + 3 = 30 - 2x \Rightarrow 7x + 2x = 30 - 3 \Rightarrow 9x = 27 \Rightarrow x = \frac{27}{9} \Rightarrow x = 3$$ 3) $$7 - 2x = 3x - 18 \Rightarrow -2x - 3x = -18 - 7 \Rightarrow -5x = -25 \Rightarrow x = \frac{-25}{-5} \Rightarrow x = 5$$