I would first of all eliminate those decimals
-4.5x-2y=-12.5
times 2 ------> -9x - 4y = -25 or 9x + 4y = 25
3.25x-y=-0.75
times 4 -------> 13x - 4y = 3
now just add them and things will work out
Solve the system by substitution
{-4.5x-2y=-12.5
3:25x-y=-0.75}
2 answers
that last equation should have been
13x - 4y = -3
13x - 4y = -3