a) \frac{3}{4} \cdot 1,8 \cdot 1\frac{1}{5} : 0,07\;\frac{\frac{1}{5}}{: 0,49 \cdot 2\frac{5}{8}}

a) Выполним действия:

1) $$1,8 = \frac{18}{10} = \frac{9}{5}$$

$$1\frac{1}{5} = \frac{6}{5}$$

$$\frac{3}{4} \cdot \frac{9}{5} \cdot \frac{6}{5} = \frac{3 \cdot 9 \cdot 6}{4 \cdot 5 \cdot 5} = \frac{3 \cdot 9 \cdot 3}{2 \cdot 5 \cdot 5} = \frac{81}{50}$$

2) $$0,07 = \frac{7}{100}$$

$$\frac{81}{50} : \frac{7}{100} = \frac{81}{50} \cdot \frac{100}{7} = \frac{81 \cdot 2}{7} = \frac{162}{7}$$

3) $$0,49 = \frac{49}{100}$$

$$2\frac{5}{8} = \frac{21}{8}$$

$$\frac{49}{100} \cdot \frac{21}{8} = \frac{49 \cdot 21}{100 \cdot 8} = \frac{1029}{800}$$

4) $$\frac{1}{5} : \frac{1029}{800} = \frac{1}{5} \cdot \frac{800}{1029} = \frac{160}{1029}$$

5) $$\frac{162}{7} : \frac{160}{1029} = \frac{162}{7} \cdot \frac{1029}{160} = \frac{81}{1} \cdot \frac{147}{80} = \frac{81 \cdot 147}{80} = \frac{11907}{80} = 148\frac{67}{80}$$

Ответ: $$148\frac{67}{80}$$