Not sure what I'm doing wrong, can someone help me, please?

Cansela Corporation uses a periodic inventory system and the LIFO method to value its inventory. The company began 2016 with inventory of 6,300 units of its only product. The beginning inventory balance of $97,900 consisted of the following layers 2,300 units at $13 per unit E 29,900 4,000 units at $17 per unit 68,000 97,900 During the three years 2016-2018 the cost of inventory remained constant at $19 per unit. Unit purchases and sales during these years were as follows Purchases Sales 2016 14,500 15.500 2017 19,000 22,000 2018 16,500 18,000