What is it called when a fee is charged by brokers only when investors are buying and selling their assets?

Record the journal entry for the provision for uncollectible accounts under each of the following independent assumptions: a. the allowance for doubtful accounts before adjustment has a credit balance of $500. b. the allowance for doubtful accounts before adjustment has a debit balance of $250. c. assume that octoberʼs credit sales were $70,000. uncollectible accounts expense is estimated at 2% of sales. smith, gaylord n.. excel applications for accounting principles (p. 51). cengage textbook. kindle edition.