Б) $$(8\frac{7}{15} - 3\frac{3}{4} + 4\frac{2}{5} - 8\frac{7}{60}) : (4\frac{1}{4} - 2\frac{3}{4})$$

Решим пример по действиям.

1. Преобразуем смешанные дроби в неправильные:
   • $$8\frac{7}{15} = \frac{8 \times 15 + 7}{15} = \frac{120 + 7}{15} = \frac{127}{15}$$
   • $$3\frac{3}{4} = \frac{3 \times 4 + 3}{4} = \frac{12 + 3}{4} = \frac{15}{4}$$
   • $$4\frac{2}{5} = \frac{4 \times 5 + 2}{5} = \frac{20 + 2}{5} = \frac{22}{5}$$
   • $$8\frac{7}{60} = \frac{8 \times 60 + 7}{60} = \frac{480 + 7}{60} = \frac{487}{60}$$
   • $$4\frac{1}{4} = \frac{4 \times 4 + 1}{4} = \frac{16 + 1}{4} = \frac{17}{4}$$
   • $$2\frac{3}{4} = \frac{2 \times 4 + 3}{4} = \frac{8 + 3}{4} = \frac{11}{4}$$
2. $$\frac{127}{15} - \frac{15}{4} + \frac{22}{5} - \frac{487}{60} = \frac{127 \times 4}{15 \times 4} - \frac{15 \times 15}{4 \times 15} + \frac{22 \times 12}{5 \times 12} - \frac{487}{60} = \frac{508}{60} - \frac{225}{60} + \frac{264}{60} - \frac{487}{60} = \frac{508 - 225 + 264 - 487}{60} = \frac{60}{60} = 1$$
3. $$\frac{17}{4} - \frac{11}{4} = \frac{17 - 11}{4} = \frac{6}{4} = \frac{3}{2}$$
4. $$1 : \frac{3}{2} = 1 \times \frac{2}{3} = \frac{2}{3}$$

Ответ: $$\frac{2}{3}$$