$(\dfrac{-1}{2})\times(\dfrac{-3}{7})$=

$\dfrac{(\dfrac{-2}{3})}{(\dfrac{-1}{3})}$=

$\dfrac{1}{3}-\dfrac{4}{3}$=

$(\dfrac{-9}{2})\times\dfrac{9}{8}$=

$(\dfrac{-1}{3}) : \dfrac{1}{2}$=

$(\dfrac{-4}{9})\times\dfrac{3}{4}$=

$(\dfrac{-2}{3})+\dfrac{7}{5}$=

$(\dfrac{-9}{5})+(\dfrac{-2}{3})$=

$\dfrac{(\dfrac{-2}{5})}{(\dfrac{-2}{3})}$=

$\dfrac{\dfrac{5}{4}}{\dfrac{3}{4}}$=