# Solve by substitution

Solve the system by substitution, if possible.
2x7y=-9
3x+14y+-10

I have tried several times and get the same answer, which is wrong. Here is what I am doing to get the answer:
2x-7y=9
-7y -7y
2x=-7y-9
/2 /2 /2
X=-7/2y-9/2

Then I substitute for x:
2(-7/2y-9/2)-7y=-9
-7y-9-7y=-9
-14y-9=-9
-14y=0
Y=0

Then I substitute for y:
2x-7(0)=-9
2x=-9
/2 /2
X=-9/2

This is not the correct answer. I need help!

 Capuchin Posts: 5,319, Reputation: 3601 Uber Member #2 Dec 8, 2008, 01:10 AM
In your first step, you need to add 7y to both sides to cancel the -7y, not subtract. You also need to substitute your equation for x into the other equation, or you'll just end up with somethign that's not useful to you.

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