Question 770914: solve by substation
x-y=10
-x-y=20
Answer by algebrahouse.com(1659)   (Show Source):
You can put this solution on YOUR website! x - y = 10
-x - y = 20
x = y + 10 {added y to each side of top equation}
-(y + 10) - y = 20 {substituted (y + 10), in for x, into bottom equation}
-y - 10 - y = 20 {distributed negative sign through parentheses}
-2y - 10 = 20 {combined like terms}
-2y = 30 {added 10 to each side}
y = -15 {divided each side by -2}
x = y + 10 {transformed top equation}
x = -15 + 10 {substituted -15, in for y, into new top equation}
x = -5 {combined like terms}
x = -5 and y = -15
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