PB5. LO 10.3 Use the first-in, first-out method (FIFO) cost allocation method, with perpetual inventory updating, to calculate (a) sales revenue, (b) cost of goods sold, and c) gross margin for B75 Company, considering the following transactions. Number of Units 7,500 8,000 500 Unit Cost $60 55 Beginning inventory Purchased Sept. 18 Sold Sept. 28 for $100 per unit