If they’re not equal to anything you can’t solve for them in a meaningful way. Simplified, it is 18x^2+12xy+54x+36y.
If these are equal to 0, it is possible to solve for them due to the fact that if either of these solve to 0, it makes them both 0. Therefore, you can set these separately equal to 0 to solve. 6x+18=0 makes x=-3, and when you plug that into the second equation 3(-3)+2y=0, you get y=4.5
Hope this helps