A company just starting business made the following four inventory purchases in June: Date - Number of units purchased - Total cost June 1 - 170 units - $ 350 June 10 - 190 units - 575 June 15 - 190 units - 640 June 28 - 200 units - 520Total = $2085A physical count of merchandise inventory on June 30 reveals that there are 220 units on hand. The inventory method which results in the highest gross profit for June is __________.