SOLUTION: I am suppose to solve the systems of equations by elimination and I don't understand it. Here is my problem. It says to solve by substitution. x-4y=22 2x+5y=-21

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Question 900834: I am suppose to solve the systems of equations by elimination and I don't understand it. Here is my problem. It says to solve by substitution.
x-4y=22
2x+5y=-21
Found 2 solutions by Jc0110, MathTherapy:
Answer by Jc0110(165) About Me  (Show Source):
You can put this solution on YOUR website!
x-4y=22 --> Equation 1
x=22%2B4y --> Equation 2 ... Substitute into Equation 3.
2x%2B5y=-21 --> Equation 3
2%2822%2B4y%29%2B5y=-21
%2844%2B8y%29%2B5y=-21
44%2B8y%2B5y=-21
44%2B13y=-21
13y=-21-44
13y=-65
y=-65%2F13
y=-5 ... Substitute into Equation 2.
x=22%2B4%28-5%29
x=22-20
x=2
Therefore, x=2 whereby y=-5.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

I am suppose to solve the systems of equations by elimination and I don't understand it. Here is my problem. It says to solve by substitution.
x-4y=22
2x+5y=-21

Which method is it: elimination, or substitution?