Đáp án:
Giải thích các bước giải:
$\dfrac{\dfrac{-6}{5}+\dfrac{6}{19}-\dfrac{6}{23}}{\dfrac{9}{5}-\dfrac{9}{19}+\dfrac{9}{23}}$
$ $
$=\dfrac{-6.(\dfrac{1}{5}-\dfrac{1}{19}+\dfrac{1}{23})}{9.(\dfrac{1}{5}-\dfrac{1}{19}+\dfrac{1}{23})}$
$ $
$=\dfrac{-6}{9}=\dfrac{-2}{3}$