Ivonne disributes fastener supplies. Her annual demand for a particular fastener is 1,000 units. The cost of placing an order is $20, while the holding cost/unit per year is 10 percent of the cost. This item currently costs $10 if the order quantity is less than 300. For orders of 300 units or more, the cost falls to $9.80. Show your work.

a) To minimize total cost, how many units should Ivonne drder each time she places an order?

b) What is the minimum total cost of inventory per year?