Вариант 2: 9/10 : 3/5 =; 4/7 : 2/3 =; 11/12 : 5/8 =; 8 : 4/5 =.

1. \(\frac{9}{10}:\frac{3}{5}=\frac{9}{10}\cdot\frac{5}{3}=\frac{3}{2}=1\frac{1}{2}\).
2. \(\frac{4}{7}:\frac{2}{3}=\frac{4}{7}\cdot\frac{3}{2}=\frac{6}{7}\).
3. \(\frac{11}{12}:\frac{5}{8}=\frac{11}{12}\cdot\frac{8}{5}=\frac{22}{15}=1\frac{7}{15}\).
4. \(8:\frac{4}{5}=8\cdot\frac{5}{4}=10\).

Ответ: \(1\frac{1}{2};\ \frac{6}{7};\ 1\frac{7}{15};\ 10\).