beautiful lawns company estimates its doubtful accounts by aging its accounts receivable and applying percentages to various aged categories of accounts. the beautiful lawns company computes a total of $3,600 in estimated doubtful accounts as of december 31, 2016. its accounts receivable account has a balance of $112,800 and its allowance for doubtful accounts has a credit balance of $600 before adjustment at december 31, 2016.