SOLUTION: solve the system of equations by substitution y=3x+7 y=x-9

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Question 865013: solve the system of equations by substitution
y=3x+7
y=x-9
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

y=3x+7 ... start with the first equation


x-9=3x+7 ... plug in y = x-9


x-9-7=3x


-9-7=3x-x


-16=2x


2x=-16


x=-16/2


x=-8


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Now use this to find y


y=x-9


y=-8-9


y=-17

So the solutions are x=-8 and y=-17