What is the after-tax cost of debt for a firm if it pays at 21% of tax rate, and pays 15% on its debt

On december 31 of the current year, the unadjusted trial balance of a company using the percent of receivables method to estimate bad debt included the following: accounts receivable, debit balance of $97,900; allowance for doubtful accounts, credit balance of $1,031. what amount should be debited to bad debts expense, assuming 6% of outstanding accounts receivable at the end of the current year are estimated to be uncollectible?