This is my home work . I think that I have done with question a, but please check it for me. In question b, I can't prepare an adjusted trial balance ( always debits 77450 - Cr 74050 ).
Thank you so much !

P/s : sorry for my bad english.

Unadjusted trial balance
As at 30 June 2011

No.	Account title	Debit	Credit
	Cash	$7750
	Account receivable	6000
	Prepaid insurance	1800
	Supplies	2000
	Office Equipment	15000
	Accumulated depreciation		$10000
	Account payable		4500
	Service Revenue received in advance		4000
	Share capital		30000
	Retained earnings		3750
	Service revenue		27900
	Salaries expense	44000
	Rent expense	1000
	Insurance expense	600
	Electricity expense	2000
		$80150	$80150

Additional information: (accounting cycle is from 1 July, 2010 to 30 June, 2011)
1. Supplies on hand at 30 June total $1000
2. An electricity bill for $150 for June has not been recorded and will not be paid until next month
3. The prepaid insurance is the annual premium for insurance commencing on 1 January 2011.
4. Services were performed during the current period in relation to $2500 of revenue received in advance in the previous period
5. Salaries of $1500 are owed at 30 June
6. Depreciation expense for the year is $2000
7. Invoices representing $3000 of services performed during the month have not been recorded as of 30 June, 2011

Required:
a. Prepare adjusting entries as at 30 June, 2011
b. Prepare an adjusted trial balance as at 30 June, 2011 (hint: find out total balance of all accounts after adjustment process)

The part I did
sorry again because I write down in the papper.Attachment 47857Attachment 47858Attachment 47859

The way to do this is correctly intrepret the question and either set up T-accounts to post your entries or set up a worksheet

Cash $7750			7750				7750
Account receivable 6000			6000		3000		9000
Prepaid insurance 1800			1800			900	900
Supplies 2000			2000			1000	1000
Office Equipment 15000			15000				15000
Accumulated depreciation $10000				10000		2000		12000
Account payable 4500				4500			0	4500
Accrued expenses						150		150
Service Revenue received in advance 4000				4000	2500			1500
Share capital 30000				30000			0	30000
Retained earnings 3750				3750			0	3750
Service revenue 27900				27900		5500		33400
Salaries expense 44000			44000				44000
Supplies expense					1000		1000
Depreciation expense					2000		2000
Rent expense 1000			1000				1000
Insurance expense 600			600		900		1500
Electricity expense 2000			2000		150		2150
$80150 $80150			80150	80150	9550	9550	85300	85300

Thank you so much!