The adjusting entries are as follows:
To record the quarterly depreciation expense (400*3=$1200) for equipment
To record one third of the unearned rent, as now earned (9900/3=$3300)
To record the quarterly accrual of interest that is payable on the notes
To record the quarterly usage of supplies, with a balance of (2800-2100)$700 left on account
To record the insurance expense of 200*3=$600 for the quarter, and reduce the prepaid insurance by the same amount
Please don't worry as every expert over here is well qualified in the field of accountancy and finance. I have a lot of previous experience with such questions, and figured out what was credit and what was debit, all by myself. the answer that I have given is bascially based on the debits and credits that you have NOW provided, which, of course, I had figured out earlier. Don't worry, the answer is correct. As a rule, if you are not given the debits and credits within a question, remember that:
unless is otherwise stated. So remember these rules and you will never get your answer wrong even if you haven't been told if an item is credit or debit.
Go ahead and accept the answer. If you are unsure or dissatisfied, you may go for a second opinion, as you wish.