For (3). Just take the constant to the other side, you're left with x and y= constant.
Here, I'll show you!
0=-36x + 14y + 8
0 = 18y -9 -27x
Best thing to do first: 36x - 14y = 8 - 0, 36x - 14y = 8
And, for the second equation: 27x - 18y = 0+9, 27x - 18y = -9.
Now, divide the first equation by 2 and the second equation by 9, because the x will end up as a canceling factor.
So, 18x-7y=4, 3x-2y=-1, try to make both x's equal, subtract find x, then solve for y!