SOLUTION: How many solutions exist for the following system of equations? -10x – 10y = 20 -10x + 6y = -108

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Question 621903: How many solutions exist for the following system of equations?
-10x – 10y = 20
-10x + 6y = -108

Answer by dragonwalker(73) About Me  (Show Source):
You can put this solution on YOUR website!
equation 1: -10x – 10y = 20
equation 2: -10x + 6y = -108
rearrange equation 1: -10x = 20 + 10y
(unless you are switching all numbers to the opposite side you should change the sign of the ones switched)
Substitute into equation 2:
20 + 10y + 6y = -108
16y = -108 - 20
16y = -128
divide both sides by 16
16y/16 = -128/16
y = -8
No substitute back into equation 1:
-10x + 80 = 20
-10x = 20-80
-10x = -60
as both negative to find x we need to change both to positive
10x = 60
divide both sides by 10
10x/10 = 60/10
x = 6