2x-3y=13
x+2y=-4
First times the second problum by 2.
2x-3y=13
2(x+2y=-4)
Your new problum is
2x-3y=13
2x+4y=-8
Now subtract both problums
2x-3y=13
-2x+4y=-8
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-7y=-21
Now divde the -7 on both sides.
-7y=-21
/7 /-7
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y=2
Now you want to substitute the y for the 2 in on of your problums.
x+2(2)=-4
Now mutiplie the 2 by the 2
x+4=-4
Now subtract the 4 on both sides to solve for x.
x+4=-4
-4 -4
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x=-8
