The Flipper Stop sells a variety of aquatic gear to swimmers, divers, and snorkelers. It currently sells a snorkel kit that is becoming quite popular.
 The graph shows the projected revenue and cost for a given month, based on the selling price of the snorkel kit.
 +3,500
 +3,000
 +2,500
 +2,000
 Total (dollars)
 +1,500
 +1,000
 1500
 20 30 40 50
 / Price per Snorkel Kit (dollars)
 60
 The selling price of the snorkelkit should be set to s
 to obtain a maximum monthly profit of about $