A retailer buys 800 USB Flash Drives per year from a distributor. The retailer wants to determine how many drives to order, x, per shipment so that her inventory is exhausted just as the next shipment arrives. The processing fee is $20 per shipment, the yearly storage cost is $1.60x, and each drive costs the retailer $4.45. (a) Express the total yearly cost C as a function of the number x of drives in each shipment. (b) Use a graphing utility to determine the minimum yearly cost and the number of drives per order that yields the minimum cost.