I have no idea how to figure this out! In need of an explanation.

Hair World Inc. is a wholesaler of hair supplies. Hair World uses a perpetual inventory system. The following transactions (summarized) have been selected for analysis: a. Sold merchandise for cash (cost of merchandise $12,797). $19,200 b. Received merchandise returned by customers as unsatisfactory (but in perfect condition), for cash refund (original cost of merchandise $120). 200 c. Sold merchandise (costing $2,850) to a customer, on account with terms 2/10, n/30. 6,000 d. Collected half of the balance owed by the customer in (c) within the discount period. 2,940 e. Granted a partial allowance relating to credit sales that the customer in (c) had not yet paid I need to find the gross profit, net sales, and gross profit percentage. 96