I am not understanding how the Bad Debts Expense was calculated.

At September 30, 2018, the accounts of Mountain Terrace Medical Center (MTMC) include the following Accounts Receivable Allowance for Bad Debts (credit balance) $ 143,000 3,700 Debit Date Credit Accounts and Explanation 2018 432,700 Dec. 31Cash Accounts Receivable 432,700 Wrote off accounts receivable as uncollectible: Silver, Co., $1,500, Oliver Welch, $900; and Paradise, Inc., $800 Debit Date Credit Accounts and Explanation 2018 3,200 Dec. 31Allowance for Bad Debts 900 800 1,500 Accounts Receivable-oliver Welch Accounts Receivable-Paradise, Inc Accounts Receivable-Silver, Co Recorded bad debts exnense based on the aging of accounts receivable More Info transa Sales on account, $490,000. Ignore Cost of Goods Sold. Collections on account, $432,700 Wrote off accounts receivable as uncollectible: Silver, Co., $1,500; Oliver Welch, $900; and Paradise, Inc., $800 Recorded bad debts expense based on the aging of accounts receivable, as follows: Age of Accounts 1-30 Days 31-60 Days 61-90 Days Over 90 Days 37,100 35% $ 101,000 $ 42,000 S 17,000 S Accounts Receivable 3% Estimated percent uncollectible 0.3% 30% Print Done Recorded bad debts expense based on the aging of accounts receivable Date Debit Credit Accounts and Explanation 2018 Dec. 31 Bad Debts Expense 19,148 19,148 Allowance for Bad Debts