`7/12 + 3/4 xx 2/9`
`= 7/12 + 1/6`
`= 9/12`
_________________
`8/9 - 4/15 : 2/5`
`= 8/9 - 2/3`
`= 2/9`
a) \(\dfrac{7}{12}+\dfrac{3}{4}\times\dfrac{2}{9}=\dfrac{7}{12}+\dfrac{1}{6}=\dfrac{7}{12}+\dfrac{2}{12}=\dfrac{3}{4}\)
b) \(\dfrac{8}{9}-\dfrac{4}{15}:\dfrac{2}{5}=\dfrac{8}{9}-\dfrac{4}{15}\times\dfrac{5}{2}=\dfrac{8}{9}-\dfrac{2}{3}=\dfrac{8}{9}-\dfrac{6}{9}=\dfrac{2}{9}\)