How do you find the solution of the system of equations $-3x+4y=12$ and $3x-6y=18$ ?

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Answer 1 · 2015-05-08T21:09:17

Given
$-3x+4y=12$
$3x-6y=18$

If you add the two equations together, you get
$-2y = 30$
$rarr y=-15$

Plug this back into the first equation:
$-3x + 4(-15) = 12$
$-3x = 72$
$rarr x= -24$

It would be a good idea to check these values with the second equation:
$3(-24)-6(-15) = -72+90 = 18 " and it all looks good!"$

How do you find the solution of the system of equations -3x+4y=12-3x+4y=12 and 3x-6y=183x-6y=18?