Put this in a descending order in terms of y: 3y - 6x*3y*2 - 2x + 12x*2y*3​

i belive those are the ones that are under 90 degreese.

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.