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

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Question 110798: Solve the system by substitution.
x + y = 12
y = 2x
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Start with the given system
x%2By=12
y=2x



x%2B%282x%29=12 Plug in y=2x into the first equation. In other words, replace each y with 2x. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



3x=12 Combine like terms on the left side


x=4 Divide both sides by 3 to isolate x




Now that we know that x=4, we can plug this into y=2x to find y



y=2%284%29 Substitute 4 for each x


y=8 Simplify


So our answer is x=4 and y=8