Bỏ ngoặc rồi tính. c ) [ ( − 2/5 ) + 1/3 ] − ( 3/5 − 1/4 ) ;

c) $[\left(\frac{-2}{5}\right)+\frac{1}{3}]-(\frac{3}{5}-\frac{1}{4})=\left(\frac{-2}{5}\right)+\frac{1}{3}-\frac{3}{5}+\frac{1}{4}$

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

$=\left(\frac{-12}{12}\right)+\frac{4}{12}+\frac{3}{12}=\frac{-5}{12}$