
Answer:
The relevant journal entry would be:
Date           Account Title                      Debit       Credit
February 1      Cash                            $600
             Accounts Receivable                          $400
              Revenue                                    $200
The entire $600 will be debited to cash to show that $600 was received in cash.
$400 will go to Accounts Receivable to cancel out the debt owed by the customer.
Revenue will be credited $200 for the amount owed through February 1st. Revenue is credited when it increases.