A. If the total cost function is C(x) = 250 + 21x + 0.1x2 dollars, producing how many units, x, will result in a minimum average cost per unit? Find the minimum average cost per unit. B. An agency charges $100 per person for a trip to a concert if 70 people travel in a group. But for each person above the 70, the charge will be reduced by $1. How many people will maximize the total revenue for the agency if the trip is limited to at most 90 people