An office manager uses 500 boxes of file folders per year. The price is $8.50 per box for an order size Q <= 200, $8.00 per box for orders of 200 < Q < 800, and $7.50 per box for an order size Q >= 800. Carrying cost is 20 percent of the price of the product. Ordering costs are $150 and all the boxes in an order will be delivered at once. What is the price at the optimal order quantity that minimizes total annual cost?