Đáp án:

 $\dfrac{2}{9}$

Giải thích các bước giải:

 $\dfrac{7}{12}$ × $\dfrac{4}{9}$ + $\dfrac{4}{9}$ × $\dfrac{5}{12}$ - $\dfrac{2}{9}$

= $\dfrac{4}{9}$ × ( $\dfrac{7}{12}$ + $\dfrac{5}{12}$ ) - $\dfrac{2}{9}$

=$\dfrac{4}{9}$ ×  1 - $\dfrac{2}{9}$

=$\dfrac{4}{9}$ - $\dfrac{2}{9}$

=$\dfrac{2}{9}$