SOLUTION: How would I solve this by substitution? I keep coming up with the wrong answer. 4x+y=-5 5x-3y=15

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Question 964767: How would I solve this by substitution? I keep coming up with the wrong answer.
4x+y=-5
5x-3y=15
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
4x+y=-5
5x-3y=15
:
rearrange the 1st equation
4x + y = -5
y = -4x - 5
:
replace y with (-4x-5) in the 2nd equation
5x - 3(-4x-5) = 15
5x + 12x + 15 = 15
17x = 15 - 15
17x = 0
x = 0
:
Find y using the 1st equation;
4(0) + y = -5
Y = -5
:
Solution: x = 0, y = -5
:
Check this in the 2nd equation
5(0) - 3(-5) = 15
15 = 15