Answer and Explanation:
The journal entries are shown below:
On July 1
Accounts receivable Dr $20,000  
             To Sales revenue  $20,000
(To record the sales on account)
On July 10
Cash $19,400    
Sales discount $600 ($20,000 × 3%)  
         To Accounts receivable  $20,000
(To record the payment received)
On July 17
Accounts receivable $200,000  
              To Sales revenue  200,000
(To record the sales on account)
On July 30
Cash $200,000  
        To Accounts receivable  $200,000
(To record the payment received)