а) $$6 : x = 36 : 30$$
$$x = \frac{6 \cdot 30}{36} = \frac{180}{36} = 5$$
Ответ: x = 5
б) $$15 - 2(x - 2) = 22 + x$$
$$15 - 2x + 4 = 22 + x$$
$$19 - 2x = 22 + x$$
$$3x = -3$$
$$x = -1$$
Ответ: x = -1