Question 185375
Given:
2x-5y = -158
 x- y = -40
.
Using the "addition method", we start by multiplying the second equation by -5:
2x-5y = -158
-5(x- y) = -5(-40)
.
Giving us:
 2x-5y = -158
-5x+5y = 200
.
Now we ADD the two equation together:
 2x-5y = -158
-5x+5y = 200
----------------
-3x    = 42
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Finally, we divide both sides by -3:
-3x    = 42
x    = -14
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To find y, we plug the above into either equation -- I'll use:
 x- y = -40
 -14- y = -40
-y = -26
y = 26
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Solution: (x,y) = (-14, 26)