Ответ:

  1. \(\frac{12}{35}:\frac{2}{5}=\frac{12}{35}\cdot\frac{5}{2}=\frac{6}{7}\).
  2. \(8\frac{3}{4}:2\frac{1}{3}=\frac{35}{4}:\frac{7}{3}=\frac{35}{4}\cdot\frac{3}{7}=\frac{15}{4}=3\frac{3}{4}\).
  3. \(\frac{15}{17}:5=\frac{15}{17}\cdot\frac{1}{5}=\frac{3}{17}\).

Ответ: 1) \(\frac{6}{7}\); 2) \(3\frac{3}{4}\); 3) \(\frac{3}{17}\).