Ivan got a job working at Carl's Jr. He makes $16 per hour. On Monday he worked 4hrs, on Wednesday he worked
3hrs and on Saturday he worked 8hrs. On Sunday he picked up his paycheck. His mom told him that he owed her for
the video game she bought him that cost $53.50. How much money did he have left after paying back his mom?

She first uses a straight edge to draw a diameter of the circle through the center.

Then, using a compass and straight edge, she constructs the perpendicular bisector of the diameter forming another diameter.

(These resulting four points on the circle are the vertices of the inscribed square.), hence, these points are joined in the next step using a straightedge.