SOLUTION: Solve the system by substitution. x + y = -7 x - y = 13

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Question 41068: Solve the system by substitution.
x + y = -7
x - y = 13
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
Okay, let us solve the first one for x and substitute that value into the second one...like this...
x + y = -7
x = -y - 7
and
-y - 7 - y = 13
-2y - 7 = 13
-2y = 20
y = -10
and
then x = 3