Irrecoverable debt

Hi, I have doubt for the question below:- In the year ended 30 sep 20x8, Fauntleroy had sales of $7,000,000. The year-end receivables amounted to 5% of annual sales. At the year end, Fauntleroy's specific allowance for receivables equated to 4% of receivables. He also identified that this amount was 20% higher than at the previous year end. During the year irrecoverable debts amounting to $3,200 were written off and debts amounting to $450 and previously written off were recovered. What was the irrecoverable debt expense for the year? My answer is B) $5,550 But the answer shown is A) 5,083. I found that the root of difference is at the point of calculating the previous year allowance for receivable. I use this year allowance receivable 4k - (4k x 20%) = 11.2k. While the answer calculating is 4k x 120%/100% = 11.667k. I would appreciate if you could help to solve my doubt. Thank you.