SOLUTION: Solve the system of equations using the elimination method: x + y = 9 1x + 3y = 15

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Question 417999: Solve the system of equations using the elimination method:
x + y = 9
1x + 3y = 15
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
1x+1y=9 .............1
1x+3y=15 .............2

multiply (1)by -3
Multiply (2) by 1
-3x-3y=-27
1x+3y=15

Add the two equations
-2x=-12
/-2
x=6
plug value of x in (1)
1x+1y=9
6+1y=9
y=9+-6
y=3
y = 3