Answer:
a. Unadjusted Trial Balance
Accounts                   Debits   Credits
Cash                       $ 47,300
Accounts Receivable 10,400
Supplies                     3,400
Equipment               19,400
Accumulated Depreciation    $ 3,800
Salaries Payable                        
Common Stock                       28,000
Retained Earnings                    8,200
Dividend                     1,100
Service revenue                    54,000
Repairs and 
maintenance exp $12,400
Totals                 $ 94,000 $ 94,000
b. Adjusted Trial Balance
Accounts                   Debits   Credits
Cash                        $ 47,300
Accounts Receivable 10,400
Supplies                        1,200
Equipment                  19,400
Accumulated Depreciation    $ 8,200
Salaries Payable                      20,700
Common Stock                       28,000
Retained Earnings                    8,200
Dividend                     1,100
Service revenue                    54,000
Repairs and 
maintenance exp    12,400
Salaries expense    20,700 
Depreciation Exp      4,400 
Office supplies exp  2,200  
Totals                    $119,100 $ 119,100
3. Income Statement for the year ended December 31, 2021
Service revenue                    54,000
Repairs and 
maintenance exp    12,400
Salaries expense    20,700 
Depreciation Exp      4,400 
Office supplies exp  2,200  39,700
Net income                         $14,300
4. Post-closing Trial Balance
Accounts                   Debits   Credits
Cash                        $ 47,300
Accounts Receivable 10,400
Supplies                        1,200
Equipment                  19,400
Accumulated Depreciation     $ 8,200
Salaries Payable                       20,700
Common Stock                        28,000
Retained Earnings                    21,400
Totals                      $78,300 $78,300
Explanation:
a) Data and Calculations:
Accounts                   Debits   Credits
Cash                       $ 17,000
Accounts Receivable 7,400
Supplies                     3,400
Equipment               12,000
Accumulated Depreciation    $ 3,800
Salaries Payable                        5,800
Common Stock                       22,000
Retained Earnings                    8,200
Totals                  $ 39,800 $ 39,800
1. March 12 Accounts receivable $20,400  Cash $33,600 Service revenue $54,000
2. May 2 Cash $17,400 Accounts receivable $17,400
3. June 30 Cash $6,000 Common stock $6,000
4. August 1 Salaries Payable $5,800 Cash $5,800
5. September 25 Repairs and maintenance expenses, $12,400 Cash $12,400
6. October 19 Equipment $7,400 Cash $7,400
7. December 30 Cash dividends $1,100 Cash $1,100
Adjusting entries:
Salaries expense $20,700 Salaries payable $20,700
Depreciation Expense $4,400 Accumulated Depreciation $4,400
Office supplies expenses $2,200 Supplies $2,200