4. Given the following data, answer questions (a) and (b). The total fixed cost for the Grand Forks Clinic is $60 per month. The total variable cost is given as follows: Quantity of Visits Supplied Total Variable Costs per Week 1 20 2 50 3 90 4 140 5 210 6 290 a. If the price per visit is $60, what is the quantity supplied? b. If the total fixed cost increases to $80 and the price per visit is $60, what is the quantity supplied