Answer:
The Journal entries are as follows:
(i) Sales revenue A/c Dr. $900
To Cash $900
(To record the correction in sales revenue)
(ii) Merchandise Inventory A/c Dr. $200
To Cost of Goods sold $200
(To record the merchandise returned)
Note:
(1) At the time of sale, the cash would have been debited with the amount of $900 and the sales revenue would have been credited with the amount of $900. Now, the cash of $900 should be credited as it was debited earlier.
(2) The inventory account also credited at the time sale, so it should be debited and the cost of goods sold debited at the time of original sale, so it need to be credited.