Probability: There are 11 shirts
in your closet, 6 blue and 5
green. You randomly select
one to wear on Monday and
then a different one on
Tuesday. You wear blue shirts
both days.

There was a 54.5% probability of you getting a blue shirt on Monda and a 50% chance on Tuesday.

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.