1. $$\frac{8}{15}:4$$ 2. $$3:\frac{3}{2}$$ 3. $$-1:\frac{3}{4}$$ 4. $$-\frac{7}{12}:(-\frac{1}{4})$$ 5. $$\frac{1}{4} \cdot 2$$ 6. $$\frac{3}{4}:\frac{4}{9}$$ 7. $$\frac{7}{9} \cdot \frac{18}{35}$$ 8. $$-\frac{4}{19} \cdot (-\frac{57}{64})$$

Решение:

1. $$\frac{8}{15}:4 = \frac{8}{15} \cdot \frac{1}{4} = \frac{2}{15}$$
2. $$3:\frac{3}{2} = 3 \cdot \frac{2}{3} = 2$$
3. $$-1:\frac{3}{4} = -1 \cdot \frac{4}{3} = -\frac{4}{3}$$
4. $$-\frac{7}{12}:(-\frac{1}{4}) = \frac{7}{12} \cdot 4 = \frac{7}{3}$$
5. $$\frac{1}{4} \cdot 2 = \frac{2}{4} = \frac{1}{2}$$
6. $$\frac{3}{4}:\frac{4}{9} = \frac{3}{4} \cdot \frac{9}{4} = \frac{27}{16}$$
7. $$\frac{7}{9} \cdot \frac{18}{35} = \frac{7 \cdot 18}{9 \cdot 35} = \frac{1 \cdot 2}{1 \cdot 5} = \frac{2}{5}$$
8. $$-\frac{4}{19} \cdot (-\frac{57}{64}) = \frac{4 \cdot 57}{19 \cdot 64} = \frac{1 \cdot 3}{1 \cdot 16} = \frac{3}{16}$$

Ответ: 1. $$\frac{2}{15}$$; 2. $$2$$; 3. -$$\frac{4}{3}$$; 4. $$\frac{7}{3}$$; 5. $$\frac{1}{2}$$; 6. $$\frac{27}{16}$$; 7. $$\frac{2}{5}$$; 8. $$\frac{3}{16}$$.