Three identical units of merchandise were purchased during July, as follows: Date Product T Units Cost July 3 Purchase $18.00 Purchase 21.00 Purchase 24.00 Total $63.00 Average cost per unit $21.00 Assume one unit sells on July 28 for $31.00. 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