Đáp án+giải thích các bước giải:
$\dfrac{-5}{9}\times\dfrac{6}{13}+\dfrac{-5}{9}\times\dfrac{7}{23}+\dfrac{5}{23}:\dfrac{9}{7}$
$=\dfrac{-5}{9}\times(\dfrac{6}{13}+\dfrac{7}{23})+\dfrac{5}{23}:\dfrac{9}{7}$
$=\dfrac{-5}{9}\times\dfrac{229}{299}+\dfrac{5}{23}:\dfrac{9}{7}$
$=\dfrac{-1145}{2691}+\dfrac{35}{207}$
$=\dfrac{-10}{39}$