1. Решим уравнение:
a) $$7.2 : 2.4 = 0.9 : x$$
$$2. 4 * 0.9 = 7.2 * x$$
$$2. 16 = 7.2 * x$$
$$x = \frac{2.16}{7.2}$$
$$x = 0.3$$
б) $$\frac{2}{x} = \frac{3}{18}$$
$$3 * x = 2 * 18$$
$$3 * x = 36$$
$$x = \frac{36}{3}$$
$$x = 12$$
Ответ: a) x = 0.3, б) x = 12