SOLUTION: when solving a linear system such as this one: 9x-7y=31 -9x+3y=-39 how do you do it? I know its a simple problem but i'm confused

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Question 769027: when solving a linear system such as this one: 9x-7y=31
-9x+3y=-39
how do you do it? I know its a simple problem but i'm confused on what to subtract or add.
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
when solving a linear system such as this one:
9x-7y=31
-9x+3y=-39
how do you do it?
----------
Since both x terms have a coefficient of 9,
9x-7y=31
-9x+3y=-39
--------------- Add
-4y = -8
etc