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.