Prepare the following adjusting entries at December 31 for Karpai Ltd:
1. Interest on notes receivable of $600 is accrued.
2. Fees earned but unbilled total $1,800.
3. Salaries earned of $ 1,200 have not been recorded.
4. Bad debt expense for the year is $900.
Use the following account titles: Service Revenue, Accounts Receivable, Interest Income, Interest Receivable, Salaries and Wages Expense, Salaries and Wages Payable, Allowance for Doubtful Accounts, and Bad Debt Expense.