Solve each system by elimination. First clear denominators.
3x/2 +y/2=-2
x/2 +y/2=0
Multiply both equations by 2:
$\displaystyle \displaystyle\left\{\begin{array}{ll}3x+y=-4\\x+y=0\end{array}\right.$
Substract the second equation from the first to eliminate y:
$\displaystyle 2x=-4\Rightarrow x=-2$
Replace x in the second (or first) equation and find y.