we can use elimination to solve these
add the two equations together
4x+4y=0
-10x— 4y=-18
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-6x = -18
divide each side by -6
x = 3
4x + 4y = 0
substitute in x=3
4*3 + 4y =0
12 + 4y =0
subtract 12 from each side
4y=-12
divide by 4
y = -3
x=3, y= -3