Three identical units of merchandise were purchased during July, as follows: Date Product T Units Cost July 3 Purchase 1 $18 10 Purchase 1 21 24 Purchase 1 24 Total 3 $63 Average cost per unit $21 Assume one unit sells on July 28 for $31. Determine the gross profit, cost of goods sold, and ending inventory on July 31 using (a) first-in, first-out, (b) last-in, first-out, and (c) average cost flow methods. Gross Profit Cost of Goods Sold Ending Inventory a. First-in, first-out b. Last-in, first-out $ C. Average $ $ $