can you help me with the adjusting entries #4,6,12 and 15. please also explain

Sullivan Equipment Sales showed the following. 2020 Jan. 15 16 20 Mar. 1 Apr. 15 2 Nov. 1 Sold $25,850 of merchandise for $30,700 to Janco; terms 3/5, n/15. Wrote off Fedun's account in the amount of $15,850. Collected the amount owing from the January 15 sale. Accepted a $12, 340, 60-day, 78 note dated this day in granting Parker Holdings a time extension on its pastdue account. Sold merchandise costing $62,850 for $72,700 to customers who used their Visa credit cards. Visa charges a 18 fee and deposits the cash electronically into the retailer's account immediately at the time of sale. Parker Holdings honoured the note dated March 1. Accepted a $25,700, three-month, 68 note dated this day in granting Grant Company a time extension on its past-due account. Sullivan's year-end. Interest was accrued on outstanding notes receivable. Bad debts are based on an aging analysis that estimated $9,700 of accounts receivable are uncollectible. Allowance for Doubtful Accounts showed an unadjusted credit balance of $1,685 on this date. Grant Company dishonoured its note dated November 1, 2020. Recovered $1,500 from Derek Holston that was previously written off. Wrote off the Grant Company account. Dec. 31 31 2021 2 Mar. 5 14 No Transactions Debit Credit 1 a. General Journal Accounts receivable - JanCo Sales - 30,700.00 30,700.00 N b. 25,850.00 Cost of goods sold Merchandise inventory 25,850.00 3 c. 15,850.00 Allowance for doubtful accounts Accounts receivable - Fedun 15,850.00 4 d. d. Cash Sales discounts Accounts receivable - JanCo 5 e. 12,340.00 Notes receivable - Parker Holdings Accounts receivable - Parker Holdings 12,340.00 6 f. Cash Credit card expense Sales 7 9 62,850.00 Cost of goods sold Merchandise inventory 62,850,00 8 h. 12,484.00 Cash Interest income Notes receivable - Parker Holdings 144.00 12,340.00 9 i. 25,700.00 Notes receivable - Grant Company Accounts receivable - Grant Company 25,700.00 10 j. 257.00 Interest receivable Interest income 257.00 11 k. 8,015.00 Bad debt expense Allowance for doubtful accounts 8,015.00 12 1. Accounts receivable - Grant Company Interest receivable Interest income Notes receivable - Grant Company 128.50 25,700.00 13 m. 1,500.00 Accounts receivable - Derek Holston Allowance for doubtful accounts 1,500.00 14 n. 1,500.00 Cash Accounts receivable - Derek Holston 1,500.00 15 o. Allowance for doubtful accounts Accounts receivable - Grant Company