Решение:
- а) $$\frac{1}{8}:\frac{3}{4} = \frac{1 \cdot 4}{8 \cdot 3} = \frac{1}{6}$$
- б) $$3\frac{1}{5}:2\frac{7}{10} = \frac{16}{5} : \frac{27}{10} = \frac{16 \cdot 10}{5 \cdot 27} = \frac{16 \cdot 2}{1 \cdot 27} = \frac{32}{27} = 1\frac{5}{27}$$
- в) $$5:19 = \frac{5}{19}$$
Ответ: a) $$\frac{1}{6}$$; б) $$1\frac{5}{27}$$; в) $$\frac{5}{19}$$