Mouse Parts produces mouse ears, white gloves and other parts that are incorporated into the production of

Question:

Mouse Parts produces mouse ears, white gloves and other parts that are incorporated into the production of Mickey Mouse souvenirs. One of the components used in production has an annual demand of 250 units, and this is constant throughout the year. Carrying cost is estimated to be $1 per unit per year, and ordering cost is $20 per order.
To minimize cost, how many units should be ordered each time an order is placed?