How can I calculate the terms in n. etc. and How do I find the second number on the Cost of Goods sold Sales Journal

Selected accounts from the chart of accounts of Ayoade Company are shown below. 101 Cash 126 Supplies 112 Accounts Receivable 157 Equipment 120 Inventory 201 Accounts Payable 401 Sales Revenue 505 Cost of Goods Sold 412 Sales Returns and Allowances 726 Salaries and Wages Expense 414 Sales Discounts The cost of all merchandise sold was 60% of the sales price. During January, Ayoade completed the following transactions. Jan. 3 Purchased merchandise on account from Parkinson Co. $10,000. 4 Purchased supplies for cash $80. 4 Sold merchandise on account to Douglas $5,250, invoice no. 371, terms 1/10, n/30. 5 Returned $300 worth of damaged goods purchased on account from Parkinson Co. on January 3. 6 Made cash sales for the week totaling $3,150. 8 Purchased merchandise on account from Denholm Co. $4,500. 9 Sold merchandise on account to Connor Corp. $6,400, invoice no. 372, terms 1/10, n/30. 11 Purchased merchandise on account from Betz Co. $3,700. 13 Paid in full Parkinson Co. on account less a 2% discount. 13 Made cash sales for the week totaling $6,260. 15 Received payment from Connor Corp. for invoice no. 372. 15 Paid semi-monthly salaries of $14,300 to employees. 17 Received payment from Douglas for invoice no. 371. 17 Sold merchandise on account to Bullock Co. $1,200, invoice no. 373, terms 1/10, n/30. 19 Purchased equipment on account from Murphy Corp. $5,500. 20 Cash sales for the week totaled $3,200. 20 Paid in full Denholm Co. on account less a 2% discount. 23 Purchased merchandise on account from Parkinson Co. $7,800. 24 Purchased merchandise on account from Forgetta Corp. $5,100. 27 Made cash sales for the week totaling $4,230. 30 Received payment from Bullock Co. for invoice no. 373. 31 Paid semi-monthly salaries of $13,200 to employees. 31 Sold merchandise on account to Douglas $9,330, invoice no. 374, terms 1/10, n/30. Ayoade Company uses the following journals. 1. Sales journal. 2. Single-column purchases journal. 3. Cash receipts journal with columns for Cash Dr., Sales Discounts Dr., Accounts Receivable Cr., Sales Revenue Cr., Other Accounts Cr., and Cost of Goods Sold Dr./Inventory Cr. 4. Cash payments journal with columns for Other Accounts Dr., Accounts Payable Dr., Inventory Cr., and Cash Cr. 5. General journal. Instructions Using the selected accounts provided: (a) Record the January transactions in the appropriate journal noted. (b) Foot and cross-foot all special journals. (c) Show how postings would be made by placing ledger account numbers and checkmarks as needed in the journals. (Actual posting to ledger accounts is not required.) SOLUTION (a), (b) & (c)