Đề bài

Thực hiện phép tính (Bằng cách hợp lí nếu có thể)

$a)\dfrac{8}{{21}} - 1\dfrac{1}{4} + \dfrac{3}{{14}} - \left( {\dfrac{{ - 13}}{{21}}} \right) + 0,25$

$b)\dfrac{5}{8}.2\dfrac{2}{5} - \dfrac{5}{8}.1\dfrac{1}{3}$

$c)\left( {\dfrac{4}{9} - \dfrac{3}{5}} \right):\dfrac{6}{5} + \left( {\dfrac{5}{9} + \dfrac{1}{5}} \right):\dfrac{6}{5}$

$d)\dfrac{6}{7}:\left( {\dfrac{3}{{26}} - \dfrac{3}{{13}}} \right) + \dfrac{6}{7}:\left( {\dfrac{1}{{10}} - \dfrac{8}{5}} \right)$