Thực hiện phép tính (bằng cách hợp lí nếu có thể). c) ( 4/9 − 3/5 ) : 1(1/5) + ( 5/9 + 1/5 ) : 1(1/5)

c) $(\frac{4}{9}-\frac{3}{5}):1\frac{1}{5}+(\frac{5}{9}+\frac{1}{5}):1\frac{1}{5}$

$=(\frac{4}{9}-\frac{3}{5}):\frac{6}{5}+(\frac{5}{9}+\frac{1}{5}):\frac{6}{5}$

$=(\frac{4}{9}-\frac{3}{5}).\frac{5}{6}+(\frac{5}{9}+\frac{1}{5}).\frac{5}{6}$

$=(\frac{4}{9}-\frac{3}{5}+\frac{5}{9}+\frac{1}{5}).\frac{5}{6}$

$=[(\frac{4}{9}+\frac{5}{9})+(\frac{1}{5}-\frac{3}{5})].\frac{5}{6}$

$=[1+\left(\frac{-2}{5}\right)].\frac{5}{6}$

$=\frac{3}{5}.\frac{5}{6}=\frac{1}{2}$