i need how my professor found these answers.

Chapter 3 Practice: The prepaid rent was paid on December 1^st for 3 months. The insurance policy was paid on December 1^st for 6 months. A count of office supplies at the end of the month showed that $440 remained. The Office Equipment was purchased on December 1^st and will be depreciated every month for 10 years with no residual value. The Unearned Revenue was from a customer deposit on November 30^th for 2 months of work that began on December 1^st.

answers :

Record the 12/31/2020 adjusting entries.

Date	Account	Debit	Credit
12/31	Rent Expense	$900
	Prepaid Rent		$900
12/31	Insurance Expense	$150
	Prepaid Insurance		$150
12/31	Supplies Expense	$767.40
	Office Supplies		$767.40
12/31	Depreciation Expense	$121.67
	Accumulated Depreciation		$121.67
12/31	Unearned Revenue	$1,450
	Service Revenue		$1,450

Record the 12/31/2020 closing entries.

Date	Account	Debit	Credit
12/31	Service Revenue	$14,245
	Income Summary		$14,245
12/31	Income Summary	10,025.57
	Accounting Expense		450.00
	Advertising Expense		1,460.00
	Utilities Expense		696.00
	Meals Expense		68.00
	Salaries Expense		5,000.00
	Payroll Tax Expense		412.50
	Rent Expense		900.00
	Insurance Expense		150.00
	Supplies Expense		767.40
	Depreciation Expense		121.67
12/31	Retained Earnings	$1,000
	Dividends		$1,000
12/31	Income Summary	$4,219.43
	Retained Earnings		$4,219.43