Ответ: $$\frac{2}{5}$$ ; $$\frac{2}{15}$$
Решаем примеры:
$$\frac{6}{35} : \frac{2}{7} = \frac{6}{35} \cdot \frac{7}{2} = \frac{6 \cdot 7}{35 \cdot 2} = \frac{3 \cdot 1}{5 \cdot 1} = \frac{3}{5}$$
$$\frac{6}{7} : \frac{4}{21} = \frac{6}{7} \cdot \frac{21}{4} = \frac{6 \cdot 21}{7 \cdot 4} = \frac{3 \cdot 3}{1 \cdot 2} = \frac{9}{2} = 4\frac{1}{2}$$
$$\frac{4}{7} : \frac{16}{49} = \frac{4}{7} \cdot \frac{49}{16} = \frac{4 \cdot 49}{7 \cdot 16} = \frac{1 \cdot 7}{1 \cdot 4} = \frac{7}{4} = 1\frac{3}{4}$$
Решаем задачу:
$$\frac{2}{8} \cdot \frac{8}{8} = \frac{2}{8} \cdot 1 = \frac{2}{8} = \frac{1}{4}$$
$$3\frac{1}{3} - 2\frac{3}{5} = \frac{10}{3} - \frac{13}{5} = \frac{10 \cdot 5 - 13 \cdot 3}{15} = \frac{50 - 39}{15} = \frac{11}{15}$$
$$\frac{1}{4} + \frac{11}{15} = \frac{1 \cdot 15 + 11 \cdot 4}{60} = \frac{15 + 44}{60} = \frac{59}{60}$$
$$\frac{59}{60} : \frac{7}{15} = \frac{59}{60} \cdot \frac{15}{7} = \frac{59 \cdot 15}{60 \cdot 7} = \frac{59 \cdot 1}{4 \cdot 7} = \frac{59}{28} = 2\frac{3}{28}$$
Ответ: $$\frac{3}{5}$$ ; $$4\frac{1}{2}$$ ; $$1\frac{3}{4}$$ ; $$2\frac{3}{28}$$