2nd question: I'm not sure if Cash: 78,000 is correct and I don't know the Retained Earnings

Journal Entries Using the Periodic Inventory System The following selected transactions were completed by Air Systems Company during January of the current year. Air Systems uses the periodic inventory system Jan. 2. Purchased $18,200 of merchandise on account, FOB shipping point, terms 2/15, n/30. 5. Paid freight of $190 on the January 2 purchase. 6. Returned $2,750 of the merchandise purchased on January 2. 13. Sold merchandise on account, $37,300, FOB destination, 1/10, n/30. The cost of goods sold was $22,400. 15. Paid freight of $215 for the merchandise sold on January 13. 17. Paid for the purchase of January 2 less the return and discount. 23. Received payment on account for the sale of January 13 less the discount. Journalize the entries to record the transactions of Air Systems Company. If an amount box does not require an entry, leave it blank. Jan. 2 Purchases 18,200 Accounts Payable 18,200 Jan. 5 Freight In 190 Cash 190 Jan. 6 2,750 Accounts Payable Purchases Returns and Allowances 2,750 37,300 X Jan. 13 Accounts Receivable Sales 37,300 x Jan. 15 Delivery Expense 215 Cash 215 Jan. 17 Accounts Payable 15,450 Purchases Discounts 309 Cash 15,141 Jan. 23 Cash 36,927 Accounts Receivable 37,300 X Closing Entries On July 31, the close of the fiscal year, the balances of the accounts appearing in the ledger of Serbian Interiors Company, a furniture retailer, are as follows: Accumulated Depreciation-Building $365,000 Inventory $115,000 Administrative Expenses 440,000 Notes Payable 100,000 Building 810,000 Retained Earnings 455,000 Cash 78,000 Sales 1,437,000 Common Stock 75,000 Sales Tax Payable 4,500 Cost of Goods Sold 775,000 Selling Expenses 160,000 Dividends 15,000 Store Supplies 16,000 Interest Expense 6,000 Store Supplies Expense 21,500 Prepare the July 31 closing entries for Serbian Interiors Company. If an amount box does not require an entry, leave it blank. July 31 Sales 1,437,000 Administrative Expenses 440,000 Cost of Goods Sold 775,000 Interest Expense 6,000 Selling Expenses 160,000 Store Supplies Expense 21,500 Cash 78,000 101 July 31 Retained Earnings Dividends 15,000