SOLUTION: -7x+y=20 9x-3y=36

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Question 148591: -7x+y=20
9x-3y=36
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.-7x%2By=20
2.9x-3y=36
You can multiply eq. 1 by 3 and add the two equations to get an equation only in x.
1.3%28-7x%2By%29=3%2820%29
1.-21x%2B3y=60
Add this to eq. 2 to get,
9x-3y-21x%2B3y=36%2B60
-12x=96
highlight%28x=-8%29
Now you can use either eq. 1 or eq. 2 to solve for y.
1.-7x%2By=20
-7%28-8%29%2By=20
56%2By=20
highlight%28y=-36%29