Algebra

I'm asked to solve the following system using elimination and say how many solutions there are:

4x - 7y = 15
-8x + 14y = -30

The answer says that there are infinitely many solutions, but I am getting 8x - 14y = 30 and -8x + 14y = -30. I think they both come up as 30 and -30, so they aren't the same. Could someone please explain how to do this?

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  1. Just multiply everything in either of your equations by -1 to see that they are really the same equation.

    2x = 4
    is the same as
    -2x = -4

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    posted by Steve

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