Please explain your answer. Thank you.

Note: Please explain to question C why they have 400. I give you the picture.

Learning Objective 3 3. Unearned Revenue bal. $800 CR E3-24 Journalizing adjusting entries and posting to T-accounts The accounting records of Mackay Architects include the following selected, unadjusted balances at March 31: Accounts Receivable, $1,500; Office Supplies, $700; Prepaid Rent, $2,240; Equipment, $8,000; Accumulated Depreciation Equipment, $0; Salaries Payable, $0; Unearned Revenue, $900; Service Revenue, $4,100; Salaries Expense, $800; Supplies Expense, $0; Rent Expense, SO; Depreciation ExpenseEquipment, $0. The data developed for the March 31 adjusting entries are as follows: a. Service revenue accrued, $700. b. Unearned revenue that has been earned, $100. c. Office Supplies on hand $300. d. Salaries owed to employees, $200. e. One month of prepaid rent has expired, $560. f. Depreciation on equipment, $120. Requirements 1. Open a T-account for each account using the unadjusted balances given. 2. Journalize the adjusting entries using the letter and March 31 date in the date column. 3. Post the adjustments to the T-accounts, entering each adjustment by letter. Show each account's adjusted balance. c. Office Supplies on hand, $300. (Assume that Mackay debits an asset account when supplies are purchased.) Date Accounts and Explanation Debit Debit Credit (c) Mar. 31 Supplies Expense 400 Office Supplies 400 To record office supplies used