Until recently, hamburgers at the city sports arena cost $5.50 each. The food concessionaire sold an average of 15,000 hamburgers on game night. When the price was raised to $5.90, hamburger sales dropped off to an average of 11,000 per night. (a) Assuming a linear demand curve, find the price of a hamburger that will maximize the nightly hamburger revenue. (b) If the concessionaire had fixed costs of $2,500 per night and the variable cost is $0.70 per hamburger, find the price of a hamburger that will maximize the nightly hamburger profit