Đáp án:
1)$\frac{5}{7}$ + $\frac{2}{3}$ : 2
= $\frac{5}{7}$ + $\frac{2}{6}$
=$\frac{30}{42}$ + $\frac{14}{42}$
=$\frac{44}{42}$
= $\frac{22}{21}$
2)$\frac{4}{5}$ - y = $\frac{4}{9}$
=$\frac{4}{5}$ - $\frac{4}{9}$
=$\frac{16}{45}$
mong hay nhất ạ
lazy clever