While reviewing outstanding accounts receivables, John's Tractor Supply Company determines that a receivable of $15,000 is now

Question:

While reviewing outstanding accounts receivables, John's Tractor Supply Company determines that a receivable of $15,000 is now uncollectable.
Required
Journalize the entry to record bad debt expense assuming that John uses a) the direct write-off method or b) the allowance method. Is the use of the direct write-off method allowed under GAAP? If so, under what circumstances?