SOLUTION: Solve by elimination method and what is the solution set? 8x-y=20 x+y=7

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Question 471401: Solve by elimination method and what is the solution set?
8x-y=20
x+y=7

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Add corrsponding sides of the two equations:
9x = 27
==> x = 3.
To get y, multiply the bottom equation by -8, to get -8x - 8y = -56.
Add this with the top equation, to get -y - 8y = -36, or -9y = -36, or y = 4.