The following information ($ in millions) comes from a recent annual report of Amazon. com, Inc.:Net sales $ 10,711Total assets 4,363End of year balance in cash 1,022Total stockholders' equity 431Gross profit (Sales-Cost of Sales) 2,456Net increase in cash for the year 9Operating expenses 2,067Net operating cash flow 702Other income (expense), net (12)a. Compute Amazon's balance in cash at the beginning of the year. b. Compute Amazon's total liabilities at the end of the year. c. Compute cost of goods sold for the year. d. Compute the income before income tax for Amazon.