Ответ:

1) \(7\frac{3}{5}:2\frac{4}{5}=\frac{38}{5}:\frac{14}{5}=\frac{38}{5}\cdot\frac{5}{14}=\frac{19}{7}=2\frac{5}{7}\).

2) \(3\frac{1}{2}:1\frac{1}{6}=\frac{7}{2}:\frac{7}{6}=\frac{7}{2}\cdot\frac{6}{7}=3\).

3) \(2\frac{2}{5}\cdot1\frac{1}{4}=\frac{12}{5}\cdot\frac{5}{4}=3\).

4) \(1\frac{1}{7}\cdot2\frac{3}{4}=\frac{8}{7}\cdot\frac{11}{4}=\frac{22}{7}=3\frac{1}{7}\).

Ответ: примеры 2 и 3.