The bookstore orders Penn State Volleyball shirts once for a selling season from a manufacturer in Malaysia. They estimate that the demand is according to a triangular distribution with a = 1500, b = 3000, and c = 2000. It costs the bookstore $5 per shirt, and they sell the shirt for $20. If at the end of the volleyball season there are any shirts left over, they have a salvage value of $3. Determine the optimal order quantity for the bookstore.