SOLUTION: Solve the system by substitution. x+y=12 y=2x

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Question 102597: Solve the system by substitution.
x+y=12
y=2x
Answer by mjgulinello(10) About Me  (Show Source):
You can put this solution on YOUR website!
Substitution means plugging one equation into the other.
So if we plug y = 2x into the first equation we get
x+%2B+2x+=+12
Combine like terms
3x+=+12
Divide both sides by 3
x+=+4
Then we can plug in that result to the second equation.
y+=+2x
y+=+2+%2A+4
y+=+8
We can check this by plugging it back into the first equation.
x%2By=12
4%2B8=12
12=12
Checks out.
That's it for this problem.