explain how to get the AVERAGE INVENTORY

I do understand where those two numbers come from

Req. 1 The Creative Space Journal Date Post. 2020 Account Titles and Explanations Ref. Debit Credit Nov. 30 Sales Revenue 112,500 Income Summary 112,500 30 Income Summary 98,950 Sales Returns 3,000 Cost of Goods Sold 67,500 Selling Expenses 16,850 General Expenses 10,500 Interest Expense 1, 100 30 Income Summary 13,550 A. Propp, Capital 13,550 30 A. Propp, Capital 18,000 A. Propp, Withdrawals 18,000 *($112,500 - $98,950) Req. 2 2020 2019 Gross margin percentage = Gross margin $42,000* Net sales revenue $109,500** = 38.4% 32% Cost of goods sold $67,500 5.5 4.9 Inventory turnover Average inventory ($10,700 + $13,700)+2 times times ($42,000) * Sales revenue ($112,500) - Sales returns ($3,000) - Cost of goods sold ($67,500) = Gross margin *Net sales revenue = $109.500 ($112.500 - $3.000)