Evaluate the inventory valuation methods used by Walmart Inc. Compare the impact of FIFO and LIFO methods on inventory valuation and cost of goods sold. Given:

• Beginning Inventory: $10,000,000
• Purchases: $50,000,000
• Sales: $40,000,000
• Ending Inventory (FIFO): $15,000,000

Compute the cost of goods sold and ending inventory under both methods.