Can someone tell me how to do this? This is so confusing to me.

Use circumcenter theorem to solve for the given values

Sade bought 21 1/2 lb. of ground beef. he used 1/4 of the beef to make tacos and 2/3 of the remainder to make quarter-pound burgers. how many burgers did he make?

The john deere company has found that revenue,in dollars, from sales of heavy-duty tractors is a function of the unit price p, in dollars, that it charges. if therevenue r is r(p)= -1/2p^2 +1900pa)how much revenue will the company generate if they sell 700 tractors? b) how many tractors does the company want to sell to maximize the revenue?