Astop sign is in the shape of a regular octagon what is the measure of each exterior angle

there are 8 sides to a regular octagon

 there is 360 degrees in a full circle

 exterior angle = 360/8 = 45 degrees

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.