Joe is interested in an inventory costing system which results in his first-month profits being as high as possible. He sells only one product, 1970 Mercedes 250 model cars for $40 a piece. On September 1st, Joe bought 10 units for $25 each. After 3 sold on September 3rd, he ordered 20 additional units for $23 each on September 4th. On September 7th, Joe sold eight units, followed by a sale of seven units on September 10th. Joe decided to enter into a purchase agreement where he would buy fifteen units every Monday for $22 apiece. He did so on September 12th, 19th, and 26th. His remaining sales for the month were as follows: September 13th: 4 units sold September 18th: 7 units sold September 22nd: 9 units sold September 25th: 11 units sold September 28th: 6 units sold Which are an inventory costing method results in higher income for Joe? Showing your work, use this method to calculate his profit as well as ending inventory value.