Shoe Stores carries a basic black dress shoe for men that sells at a rate of 500 each quarter. Their current policy is to order 500 per quarter, with a fixed cost of $30/order. The annual holding cost is 20% of the cost of items held. The following cost structure is applicable:
Order Quantity Price/pair
0-99 $36
100-199 32
200-299 30
300+ 28
For a price of $36, the optimal order quantity is?