$\dfrac{1}{2}-\dfrac{1}{4}$=

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

$(\dfrac{-7}{4}) : (\dfrac{-3}{2})$=

$(\dfrac{-6}{7}) : (\dfrac{-3}{4})$=

$(\dfrac{-8}{9})-(\dfrac{-7}{8})$=

$\dfrac{(\dfrac{-8}{7})}{\dfrac{7}{6}}$=

$(\dfrac{-5}{9})+(\dfrac{-7}{3})$=

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

$\dfrac{\dfrac{3}{4}}{(\dfrac{-5}{2})}$=

$(\dfrac{-8}{3})+(\dfrac{-7}{4})$=