At January 1, 2023, Betty DeRose, Inc. had an allowance for doubtful accounts with a $2,700 credit balance. During 2023, Betty did not write-off any accounts receivable as uncollectible. However, during 2023, Betty recorded $1,800 of recoveries of accounts receivable written off in prior years. Betty prepared the following aging schedule at December 31, 2023: % Uncollectible 2% Accounts Receivable not past due $150,000 1-30 days past due 35,000 31-60 days past due ? 61-90 days past due 8,000 over 90 days past due 2,000 8% 12% 40% Based on the above information, Betty DeRose, Inc. estimated its bad debt expense to be $6,120 for 2023. Calculate the amount of accounts receivable that were 31-60 days past due