SOLUTION: Solve: (2x - y = 10 (x + 3y = -9 (Use substitution.)

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Question 141018: Solve:
(2x - y = 10
(x + 3y = -9 (Use substitution.)
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
2x-y=10 multiply this equation by 3 & add them.
6x-3y=30
x+3y=-9
----------------
7x=21
x=21/7
x=3 answer.
2*3-y=10
6-y=10
-y=10-6
-y=4
y=-4 answer.
proof
3+3*-4=-9
3-12=9
-9=-9