Unearned rent at 1/1/1X was $6,000 and at 12/31/1X was $15,000. The records indicate cash receipts from rental sources during 201X amounted to $40,000, all of which was credited to the Unearned Rent Account. You are to prepare the missing adjusting entry. Please indicate DR (debit) or CR (credit) to the left of the account title, and place a comma between the account title and the amount of the adjustment.