In January 2019, United Airlines (UAL) had a market capitalization of $22.9 billion, debt of $13.4 billion, and cash of $4.0 billion. United Airlines had revenues of $41.3 billion. Southwest Airlines (LUV) had a market capitalization of $27.5 billion, debt of $3.4 billion, cash of $3.7 billion, and revenues of $22.0 billion. a. Compare the market capitalization-to-revenue ratio (also called the price-to-sales ratio) for United Airlines and Southwest Airlines. b. Compare the enterprise value-to-revenue ratio for United Airlines and Southwest Airlines. c. Which of these comparisons is more meaningful? Explain.