Explanation:
The journal entries are as follows
a. 
Merchandise Inventory A/c $254,500
               To Accounts payable A/c $254,500
(Being merchandise purchased on credit)
b. 
Account payable Dr $30,000
          To Merchandise inventory $30,000
(Being the merchandise returned is recorded)
c. 
Account payable Dr $224,500        ($254,500 - $30,000)
         To Cash $224,500
(Being the payment of the invoice is recorded)