The following trial balance was taken from the books of ABC Corporation on December 31, 2020 before any adjustments were made. Cash Account Accounts Receivable Notes Receivable Allowance for Doubtful Accounts Inventory Prepaid Insurance Equipment Accumulated Depreciation--Equip. Accounts Payable Common Stock Retained Earnings Sales Revenue Cost of Goods Sold Salaries and Wages Expense Prepaid Rent Dividends Totals Debit $ 9,000 Credit 40,000 10,000 $ 1,800 34,000 4,800 100,000 15,000 10,800 46,000 55,000 260,000 126,000 50,000 12,000 2,800 $388,600 $388,600 At year end, the following items have not yet been recorded. a. Insurance expired during the year, $2,000. b. Estimated bad debts, 1% of gross sales. c. Depreciation on equipment, 10% per year on original cost. d. Interest at 6% is receivable on the note for 6 months. e. 1-year rent was paid in advance at September 1, 2020. f. Accrued salaries and wages at December 31, $5,800. Required: (a) Prepare the necessary adjusting entries. (b) Prepare the necessary closing entries.