answer is 7,700 but dont know how to get there

Atkinson Company's beginning inventory on January 1, 2008 consisted of 2,100 units costing $1.50 per unit. Purchases during the year were as follows: A physical count at year end indicated that there were 5,000 units on hand. All sales during the years were made at a selling price of $6 per unit. b. Assuming the use of the last-in, first-out inventory costing method, determine ending inventory