3. Решим уравнения.
а) $$x ∶ 103.2 = 5.6 ∶ 17.2$$
$$x = \frac{103.2 \times 5.6}{17.2} = \frac{577.92}{17.2} = 33.6$$.
б) $$11\frac{1}{5} ∶ 7 = 10\frac{1}{2} ∶ x$$
$$\frac{56}{5} ∶ 7 = \frac{21}{2} ∶ x$$
$$\frac{56}{5} \times x = \frac{21}{2} \times 7$$
$$\frac{56}{5}x = \frac{147}{2}$$
$$x = \frac{147}{2} ∶ \frac{56}{5} = \frac{147}{2} \times \frac{5}{56} = \frac{147 \times 5}{2 \times 56} = \frac{735}{112} = \frac{105}{16} = 6\frac{9}{16}$$.
Ответ: а) x = 33.6; б) $$x = 6\frac{9}{16}$$.