Computer Pro Inc. (CPI) began the month of September with 20 computers; each unit cost $45. Following are a listing of transactions that took place in the month of September for CPI:

-September 3 - Purchased 40 computers at $50 each

-September 11 - Sold 52 computers at $90 each

-September 17 - Purchased 40 computers at $55 each

-September 23 - Sold 35 computers at $90 each

Required: Calculate Cost of Goods Sold, ending inventory, and gross margin for CPI under the following cost flow assumptions: (1) FIFO, (2) LIFO, and (3) weighted average.