Please show work and write clearly. Thanks!

Estimated sales for Ackerman Company in the first quarter are shown below by month. Ackerman has a policy of having 50% of the following month's estimated sales on hand in merchandise inventory at the end of each month. On December 31, the actual merchandise inventory will be $20,000. The cost of goods sold is 80% of sales. What is the cost of the merchandise Zippy should purchase during January