[tex]\displaystyle\\7)\\\\\begin{cases}x-2y=-2\\-x+y=3\\\end{cases}\\\\---------\text{We add Equation 1 to Equation 2.}\\~~~/~~-y=1~~\Big|\cdot(-1)\\\boxed{y=-1}\\\\x-2y=-2\\x=2y-2\\x=2\cdot(-1)-2\\x=-2-2\\\boxed{x=-4}[/tex]
