Anticipated unit sales for January are 5,000; sales for February are 4,000; and sales for March are 8,000. Finished goods are consistently maintained at 80% of the following month's sales. If units cost $10 each to produce, how much is February's total cost of production? I understand the answer is $72,000 but I don't understand how to get that number, can you please show me how to get to that.