Final answer:
Smart Touch Learning would make an adjusting entry by debiting $600 to the office supplies expense account and crediting $600 to the office supplies asset account.
Step-by-step explanation:
When Smart Touch Learning purchased $1,000 of office supplies on December 1 and only $400 of office supplies remains at the end of the accounting period on December 31, it implies that $600 worth of supplies has been used. To accurately reflect this in their financial records, Smart Touch Learning would need to record an adjusting entry on December 31. The adjusting entry would consist of a debit to the office supplies expense account and a credit to the office supplies asset account for the amount of supplies used, which is $600.
The self-check question regarding the firm's accounting profit can be answered by subtracting the total expenses from the sales revenue. The firm had sales revenue of $1 million and total expenses of $950,000 ($600,000 labor + $150,000 capital + $200,000 materials), resulting in an accounting profit of $50,000.