Visa Inc.

Visa Inc. reported an income statement for the year ended September 30, 2023, with total revenue amounting to $25,900 million and operating expenses of $9,750 million. The company's gross profit stood at $16,150 million, and after accounting for interest expenses of $300 million and income taxes of $4,000 million, Visa Inc. reported a net income of $11,850 million.

a. Calculate Visa Inc.'s gross profit margin. b. Determine the operating income margin for Visa Inc. c. Discuss the impact of Visa Inc.'s interest expense on its profitability. d. Analyze the effective tax rate of Visa Inc.