Which of the following transactions do NOT affect bdd debt expense? Select all that apply. $(3$ points$)$

receiving a cheque from a customer whose account receivable was previously written off

giving a cash refund to a customer who returned an item that he had already paid for

using the aging method when estimating the required Allowance for Doubtful Accounts

writing off an account receivable

$$ applying the same percentage to all outstanding accounts receivable when estimating the required Allowance for Doubtful Accounts