Interpreting Cash Flow Information The 2020 statement of cash flows for Apple Inc. is presented below (all \$ amounts in millions): continued continued from previous page REQUIRED a. Did Apple's accounts receivable go up or down in 2020? Apple reported net sales of $274,515 in its fiscal 2020 income statement. What amount of cash did Apple collect from customers during the year? (Ignore the Vendor nontrade receivables account, which relates to Apple's suppliers.) b. Apple's cost of goods sold was $169,559 million in 2020. Assuming that accounts payable applies only to the purchase of inventory, what amount did Apple pay to purchase inventory in 2020? c. At September 30, 2020, Apple reported a balance of $36.8 billion in property, plant, and equipment, net of accumulated depreciation, and its disclosure notes revealed that depreciation expense on property, plant, and equipment was $9.7 billion for fiscal 2020 . What was the balance in property, plant, and equipment, net of accumulated depreciation at the end of fiscal 2019 ? d. Apple lists stock-based compensation as a positive amount- $11,056 million-under cash flow from operating activities. Why is this amount listed here? Explain how this amount increases cash flow from operating activities