Bài 2 (1,5 điểm) Thực hiện phép tính (tính nhanh nếu có): a) $\frac{-5}{7}$. $\frac{14}{25}$  b) $\frac{-2}{5}$. $\frac{5}{8}$ + $\frac{5}{8}$. $\frac{3}{5}$  c) 25% - $1\frac{1}{2}$+ $0,5.\frac{12}{5}$ 

`a)` $\frac{-5}{7}$ . $\frac{14}{25}$

` =` $\frac{- 2}{5}$

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`b)` $\frac{-2}{5}$ . $\frac{5}{8}$ + $\frac{5}{8}$ . $\frac{3}{5}$ 

`=` $\frac{5}{8}$ . ($\frac{-2}{5}$ + $\frac{3}{5}$)

`=` $\frac{5}{8}$ . $\frac{1}{5}$ 

`=` $\frac{1}{8}$

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$\text{c) 25% - 1$\frac{1}{2}$ + 0,5 . $\frac{12}{5}$ }$

$\text{= $\frac{1}{4}$ - $\frac{3}{2}$ + $\frac{1}{2}$ . $\frac{12}{5}$}$

`=` $\frac{5}{20}$ - $\frac{30}{20}$ + $\frac{24}{20}$

`=` $\frac{-1}{20}$

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