Question 1189990
x+2y=-1
4x-4y=20
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And?  If you want to solve for x & y, you should say, "Solve for x & y"
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x+2y=-1
4x-4y=20 ---> x - y = 5
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x + 2y=-1
x - y = 5
--------------------------- Subtract
3y = -6
y = -2
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x - y = 5
x + 2 = 5
x = 3