想請教有關中會應收帳款的問題 - 會計

做題目遇到的問題，可是沒有解釋，實在是不懂原因

A company used an estimate of 5% of outstanding receivables in adjusting

its allowance for uncollectible accounts. If failed to write off an

uncollectible account of $3,000 before adjusting its allowance to an amount

equal to 5% of its outstanding receivables. The effect of this error is to

(A) Decrease net income by $3,000

(B) Increase net income by $3,000

(C) Increase net income by $2,850

(D) No affect net income

答案是C

我選B，不太了解為什麼會是2850...

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