Cho biểu thức A - ( 7 - 2/5 + 1/3) - (6 - 4/3 + 6/5) - (2 - 8/5 + 5/3)

* Hướng dẫn giải

$A=\left(7-\frac{2}{5}+\frac{1}{3}\right)-\left(6-\frac{4}{3}+\frac{6}{5}\right)-\left(2-\frac{8}{5}+\frac{5}{3}\right)$

$A=7-\frac{2}{5}+\frac{1}{3}-6+\frac{4}{3}-\frac{6}{5}-2+\frac{8}{5}-\frac{5}{3}$

$A=\left(7-6-2\right)+\left(\frac{-2}{5}-\frac{6}{5}+\frac{8}{5}\right)+\left(\frac{1}{3}+\frac{4}{3}-\frac{5}{3}\right)$

A = -1+ 0 + 0 = -1