Help working through would be great - unsure of my answer

Glorious Gadgets is a retailer of astronomy equipment. They purchase equipment from a supplier and then sell it to customers in their store. The function C(m) = 3.52: + 997503' 1 + 28500 models their total inventory costs (in dollars) as a function of a: the lot size (the total number of pieces of astronomy equipment) for each of their orders from the supplier. The inventory costs include such things as purchasing, processing, shipping, and storing the equipment. What lot size should Glorious Gadgets order to minimize their total inventory costs? [3 What is their minimum total inventory cost? $[:]