Thực hiện phép tính

* Hướng dẫn giải

a) $\frac{3}{4}:(\frac{-7}{5}.\frac{-3}{2})$ 

$=\frac{3}{4}:\frac{(-7).(-3)}{5.2}=\frac{3}{4}:\frac{21}{10}$ 

$=\frac{3}{4}.\frac{10}{21}=\frac{3.10}{4.21}=\frac{30}{84}$ 

$=\frac{30:6}{84:6}=\frac{5}{14}$ 

b) $\frac{-1}{9}.\frac{3}{5}+\frac{-1}{9}.\frac{-4}{5}-\frac{1}{9}.0,4$ 

$=\frac{1}{9}.\frac{-3}{5}+\frac{1}{9}.\frac{4}{5}-\frac{1}{9}.\frac{2}{5}$ 

$=\frac{1}{9}.(\frac{-3}{5}+\frac{4}{5}-\frac{2}{5})$ 

$=\frac{1}{9}.\frac{(-3)+4-2}{5}$ 

$=\frac{1}{9}.\frac{-1}{5}=\frac{1.(-1)}{9.5}=\frac{-1}{45}$