please explain

Required information [The following information applies to the questions displayed below] A company began January with 9,000 units of its principal product. The cost of each unit is $5. Inventory transactions for the month of January are as follows: - Includes purchase price and cost of freight. 10.000 units were on hand at the end of the month. Required: 1. Calculate January's ending inventory and cost of goods sold for the month using FIFO, periodic system