What is cost of goods sold using the (a) FIFO, (b) LIFO, and (c) weighted average cost methods

Oahu Kiki tracks the number of units purchased and sold throughout each accounting period but applies its inventory costing method at the end of each month, as if it uses a periodic inventory system. Assume Oahu Kiki's records show the following for the month of January. Sales totaled 330 units.

Date Units Unit Cost Total Cost Beginning Inventory January 1 300 $ 90 $ 27,000 Purchase January 15 400 100 40,000 Purchase January 24 300 120 36,000