$\dfrac{2}{7}+\dfrac{1}{2}$=

$(\dfrac{-8}{9})+(\dfrac{-3}{2})$=

$(\dfrac{-8}{3})+\dfrac{6}{5}$=

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

$\dfrac{9}{8}+\dfrac{9}{5}$=

$(\dfrac{-2}{3})+\dfrac{4}{9}$=

$\dfrac{3}{5} : \dfrac{8}{5}$=

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

$\dfrac{4}{3}-\dfrac{2}{3}$=

$\dfrac{\dfrac{1}{2}}{(\dfrac{-2}{5})}$=