Let's go step by step to address each part of the problem.

1. Journalize the $8,900 write-off.

The write-off of bad debt requires a journal entry to remove the uncollectible amount from both the accounts receivable and the allowance for doubtful accounts. The entry will look like this:

Journal Entry:

Date	Account	Debit	Credit
	Allowance for Doubtful Accounts	$8,900
	Accounts Receivable		$8,900
	(Record write-off of defaulted account)

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2. Determine the desired postadjustment balance in allowance for doubtful accounts.

Now, we need to calculate the desired postadjustment balance based on the aging method using the given data. For each category, we multiply the amount of receivables by the proportion expected to default, then sum them up.

Aging Schedule Calculation:

• 0-20 days:
  $79,800 × 0.02 = $1,596
• 21-40 days:
  $21,500 × 0.08 = $1,720
• 41-60 days:
  $11,700 × 0.15 = $1,755
• Over 60 days:
  $5,300 × 0.30 = $1,590

Total desired balance in allowance for doubtful accounts:
$1,596 + $1,720 + $1,755 + $1,590 = $6,661

This is the desired postadjustment balance for allowance for doubtful accounts.

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3. Compute bad debt expense and prepare the adjusting entry.

The next step is to calculate the bad debt expense. Before the $8,900 write-off, the balance in the allowance for doubtful accounts was a debit of $450. After the write-off, the balance would be:

• Post-write-off balance: Debit of $450 - $8,900 = $9,350 debit balance.

To reach the desired credit balance of $6,661 in allowance for doubtful accounts, we need to adjust the bad debt expense. The adjusting entry must convert the debit of $9,350 to a credit of $6,661. Thus, the bad debt expense will be the sum of $9,350 (to eliminate the debit balance) and $6,661 (to reach the desired credit balance).

Bad Debt Expense Calculation:
$9,350 + $6,661 = $16,011

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Journal Entry to Record Bad Debt Expense:

Date	Account	Debit	Credit
	Bad Debt Expense	$16,011
	Allowance for Doubtful Accounts		$16,011
	(Record adjusting entry for bad debt expense estimate)

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Summary:

1. The $8,900 write-off journal entry is:

   • Debit Allowance for Doubtful Accounts: $8,900
   • Credit Accounts Receivable: $8,900

2. The desired postadjustment balance in Allowance for Doubtful Accounts is $6,661.

3. The bad debt expense is $16,011, and the adjusting journal entry is:

   • Debit Bad Debt Expense: $16,011
   • Credit Allowance for Doubtful Accounts: $16,011

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Do you need further clarification on any step? Here are 5 related questions to expand on this:

1. How does the aging method differ from the percentage of sales method for estimating bad debts?
2. What is the purpose of having an allowance for doubtful accounts?
3. Why is the bad debt expense recorded as an adjusting entry at the end of the period?
4. How would the bad debt expense change if the aging categories had higher or lower default rates?
5. What are the effects of write-offs on the financial statements?

Tip: Always ensure the allowance for doubtful accounts reflects a realistic estimate of uncollectible receivables to avoid overstating assets.