11. HEALTH CLUBS Last year, the Sports Time Athletic Club charged $20 to participate in an acrobics class. Seventy people attended the classes. The club wants to increase the class price this year. They expect to lose one customer for each $1 increase in the price. a. What price should the club charge to maximize the income from the acrobics classes? b. What is the maximum income the Sports Time Athletic Club can expect to make?​