A grocery store orders frozen pies in batches from a bakery and sells them in the grocery store. Storing one frozen pie for a year costs $0.25. When the grocery store reorders pies, there is a fixed cost of $5.25 per order as well as $0.75 per pie. Each year, they sell 4750 frozen pies.

What is the optimal number of pies to order in each order to minimize their total inventory costs.