Answer:
$390000
Step-by-step explanation:
Given: Beginning inventory= $60000
 Cost of goods purchased = $380,000
 Sales revenue= $800000.
 Ending inventory= $50000.
The Periodic inventory system is used to determine the amount of inventory available at the end of each accounting period.
Cost of goods sold= 

⇒ Cost of goods sold= 

⇒ Cost of goods sold= 

∴ Cost of goods sold= 
 .
.
Hence, $390000 is the cost of goods sold under a periodic system.