could someone explain me the answers that are wrong? thanks!!!

At the end of January 2018, the records of Regina Company showed the following for a particular item that sold at $18 per unit: Transactions Units 500 (400) 600 (300) 160 Amount $2,500 Inventory, January 1, 2018 Sale, January 10 Purchase, January 12 Sale, January 17 Purchase, January 26 3,600 1,280 Required: 1. Assuming the use of a perpetual inventory system, prepare a summarized statement through gross profit on sales under each of the following inventory costing methods: (a) weighted-average cost, (b) FIFO, and (c) specific identification, assuming that the company is permitted to use this method. For specific identification, assume that the first sale was out of the beginning inventory and the second sale was out of the January 12 purchase. (Round your intermediate calculations to 2 decimal places and final answers to nearest whole dollar amount.) Answer is not complete. REGINA COMPANY Partial Statement of Earnings For the Month Ended January 31, 2018 (a) (b) (c) Weighted- Average Cost Specific Identification FIFO $ Sales revenue 12,600 $ 12,600 12,600 Cost of sales 3,757 3,680(x 4,880 8,843 8,920 7,720