Question 747338: Solve by substitution.
X+3Y=15
2x-3y=3
Found 2 solutions by lynnlo, timvanswearingen:
Answer by lynnlo(4176)   (Show Source):
You can put this solution on YOUR website! x=-12,,,,,,,,,,y=9
Answer by timvanswearingen(106)  (Show Source):
You can put this solution on YOUR website! To use substitution, you need to solve for one of the variables in terms of the other. I usually try to go for the easiest one, so I'm going to solve for x in the first equation.
Subtract 3y from both sides:
Now you have solved for x in terms of y.
Next, use the OTHER equation, not the one you used to solve for x.
Plug in 15-3y for x.
Distribute,
Combine like terms,
Subtract 30 from both sides,
Divide both sides by -9:
Now, plug in 3 for y into the equation where x is by itself.
Now you have x and y, so your answer is the ordered pair:
(6, 3)
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