1 Answer

Sigfredo · Answer 1 · 2019-03-02T18:59:47+0000

Multiply everything on the second equation by 2, and everything on the first one by -1.

$2(2x+3y)=2(15)\\4x+6y=30$

$-1(4x+2y)=-1(18)\\-4x-2y=-18$

Then you add the equations.

$4x+6y=30\\-4x-2y=-18\\\\4y=12\\y=12/4\\y=3$

We substitute into the first equation (it could be the second) to find x:

$4x+2y=18\\\\4x+2(3)=18\\4x+6=18\\4x=18-6\\4x=12\\x=12/4\\x=3$

Now, we substitute into the second equation (again, could be the first; just don't use the same equation in these 2 steps):

$2x+3y=15\\2(3)+3(3)=15\\6+9=15\\15=15$

We are correct, so our answers should be:

$x=3\\y=3$

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