So we cant do anything until the 'y' in the 2nd problem is by the 2x. So after we move the 2x over the equation will look like this, "-2x+y=-6."
Now that that is set up we can make our equation.
(12x+5y=30) - (-2x+y=-6)
We have to multiply the second equation by -6 in order to cancle out the X's. That comes out to (12x-6y=36)
Now the equation looks like (12x+5y=30) - (12x+6y=36)
After you subtract you have (-y=-6)
divide by (-1) and you're left with y=6
