SOLUTION: Solve by substitution: x+y=12 y=3x

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Question 34476: Solve by substitution:
x+y=12
y=3x
Answer by Prithwis(166) About Me  (Show Source):
You can put this solution on YOUR website!
x+y=12
y=3x
x+3x=12
4x=12
x=3
3+y=12
y=9
(x,y) = (3,9)