Answer:
Inventory  1500	
 Accounts Payable  1500
--to record purchase--  	
Inventory  	
 Cash  
--to record payment of freights--  	
Accounts Payable  200	
 Inventory  200
--to record returned goods--  	
Accounts Payable  1300	
 Inventory  26
 Cash  1274
--to record payment within discount--  	
Inventory  90	
 Cash  90
--to record payment of freights--  	
Accounts Receivables  1600	
 Sales Revenues  1600
--to record sale--  	
COGS  800	
 Inventory  800
--to record COGS of the previous sale--    
Sales Returns  160	
 Accounts Receivables  160
--to record returned goods--  	
Cash  1,440
 Accounts Receivables  1440
--to record collection--  	
Inventory  80
           COGS          80
--to record returned but, useful goods--  
Explanation:
We reduct from the balance of the account the returrned goods: 
1,500 - 200 = 1,300 then we calcualte the discount of 2 = 26
net cash outlay: 1,300 - 26 = 1,274
The freight are part of the necessary cost to acquire the goods so it increase the inventory valuation
as the returned goods are still in good conditions we can returned to our nventory and decrease thecost of good sold associate with the sale.