Any insight on this problem would be much appreciated!

A clothing company determines a $120 for a pair of jeans they sell 800 pairs, and if they increase price by $1 then 2 less jeans are sold. They know that it they sell q jeans their cost for making those jeans is 2000 + 0.5q^2. a. Write an equation that relates q and p, the price of the jeans. b. Find the total revenue, R(x). c. Find the total profit, P(x). d. What number of jeans should the company sell to optimize their revenue