SOLUTION: Solve the system by substitution. x – 4y = –9 2x + 2y = 12 Show all work

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Question 117084: Solve the system by substitution.
x – 4y = –9
2x + 2y = 12
Show all work

Answer by misscrt(37) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the system by substitution.
x – 4y = –9 (Eqn 1)
2x + 2y = 12 (Eqn 2)
Show all work
First, solve Eqn 1 for x:
x = -9 +4y (Eqn 3)
Then, plug Eqn 3 into Eqn 2:
2(-9+4y) + 2y = 12
-18 + 8y + 2y = 12
Combine like terms:
-18 + 10y = 12
Add 18 to both sides:
-18+18 + 10y = 12 + 18
10y = 30
y = 30/10 = 3
Now find x using Eqn 3:
x = -9 +4(3)
x = -9 + 12
x = 3
Hope that helps.
misscrt