can you explain how it is you get the cost of goods sold? I've literally got every problem right but that, how do you do it? I know it's simple can you explain it in simple terms.

TrackR, Incorporated, (TI) has developed a coin-sized tracking tag that attaches to key rings, wallets, and other items and can be prompted to emit a signal using a smartphone app. Ti sells these tags, as well as water-resistant cases for the tags, with terms FOB shipping point. Assume TI has no inventory at the beginning of the month, and it has outsourced the production of its tags and cases. Ti uses FIFO and has entered into the following transactions: January 2 TI purchased and received 300 tags from Xioasi Manufacturing (XM) at a cost of $9 per tag, n/15. January 4 TI purchased and received 100 cases from Bachittar Products (BP) at a cost of $2 per case, n/20. January 6 TI paid cash for the tags purchased from XM on January 2. January 8 TI mailed 200 tags via the U.S. Postal Service (USPS) to customers at a price of $30 per tag, on account. January 11 TI purchased and received 400 tags from XM at a cost of $12 per tag, n/15. January 14 TI purchased and received 200 cases from BP at a cost of $3 per case, n/20. January 16 TI paid cash for the cases purchased from BP on January 4. January 19 TI mailed 160 cases via the USPS to customers at a price of $10 per case, on account. January 21 TI mailed 300 tags to customers at a price of $30 per tag, on account. Answer is complete but not entirely correct. No Date General Journal Credit Debit 2,700 1 January 02 Inventory Accounts Payable 2,700 N January 04 200 Inventory Accounts Payable 200 3 January 06 2,700 Accounts Payable Cash 2,700 4 January 08 6,000 Accounts Receivable Sales Revenue 6,000 5 January 08 200 X Cost of Goods Sold Inventory 200 6 09 January 11 4,800 Inventory Accounts Payable 4.800 7 January 14 600 Inventory Accounts Payable 600 8 January 16 200 Accounts Payable Cash 200 January 19 1,600 Accounts Receivable Sales Revenue 1,600 10 January 19 1,600 Cost of Goods Sold Inventory 1,600 11 January 21 9,000 Accounts Receivable Sales Revenue 9,000 12 January 21 3,150 Cost of Goods Sold Inventory 3,150