please explain why the answers are what they are. 1 is D, 2 is B, 3 D. please give a detailed explanation (atleast 2 sentences)

1) A company purchased $1,800 of merchandise on July 5 with terms 2/10, n/30. On July 7, it returned $200 worth of merchandise. On July 8, it paid the full amount due. The amount of the cash paid on July 8 equals: 1) A) $1,564. B) $1,600. C) $200. D) $1,568. E) $1,800 2) Mega Skateboard Supplier had net sales of $2.8 million, its cost of goods sold was $1.6 million, and its net income was S0.9 million. Its gross margin ratio equals: 2) A)57%. B)43%. C) 5690, D)175%. E)32%. 3) A company purchased $1,800 of merchandise on July 5 with terms 2/10, n/30. On July 7, it returned S200 worth of merchandise. On July 12, it paid the full amount due. Assuming the company uses a perpetual inventory system, and records purchases using the gross method, the correcet journal entry to record the payment on July 12 is: 3) A) Debit Merchandise Inventory $1,600; credit Cash $1,600 B) Debit Cash $1,600; credit Accounts Payable $1,600. C) Debit Accounts Payable $1,600; credit Cash $1,600. D) Debit Accounts Payable $1,600; credit Merchandise Inventory $32; credit Cash $1,568. E) Debit Accounts Payable $1,800; credit Cash $1,800