Littleton Books has the following transactions during May.

May $2$ Purchases books on account from Readers Wholesale for $$2,800,$ terms $3/10,$ n$/30.$

May $3$ Pays cash for freight costs of $$150$ on books purchased from Readers.

May $5$ Returns books with a cost of $$300$ to Readers because part of the order is incorrect.

May $10$ Pays the full amount due to Readers.

May $30$ Sells all books purchased on May $2($less those returned on May $5)$ for $$3,500$ on account.

Required:

$1.$ Record the transactions of Littleton Books, assuming the company uses a periodic inventory system.

$2.$ Record the period$-$end adjusting entry to cost of goods sold on May $31,$ assuming the company has no beginning or ending inventory.