ж) $$12\frac{1}{2} : \frac{3}{4} = \frac{25}{2} : \frac{3}{4} = \frac{25}{2} \cdot \frac{4}{3} = \frac{25 \cdot 4}{2 \cdot 3} = \frac{100}{6} = \frac{50}{3} = 16\frac{2}{3}$$
Ответ: $$16\frac{2}{3}$$