Castle company provides estimates for its uncollectible accounts. the allowance for uncollectible accounts had a credit balance of $18,080 at the beginning of 2021 and a $24,010 credit balance at the end of 2021 (after adjusting entries). if the direct write-off method had been used to account for uncollectible accounts (bad debt expense equals actual write-offs), the income statement for 2021 would have included bad debt expense of $18,700 and revenue of $3,800 from the collection of previously written off bad debts. required: determine bad debt expense for 2021 according to the allowance method.