what is the industry supply?

Suppose that you own a car wash and that its total cost fuction is: C= 20 + 2Q + .3Q^2, where C = total cost (in dollars) per hour and Q is the number of cars washed per hour. You receive 5 dollars for each car washed.

A. What is the optimal number of cars to wash per hour?

B. What is the maximum profit that uou can obtain?

C. Derive the firms short run supply curve?

D. If there are 6 identical firms, what is the industry supply?