In early 2015, United Airlines (UAL) had a market capitalization of $ 24.80 billion, debt of $ 12.80 billion, and cash of $ 5.50 billion. United Airlines had revenues of $ 38.90 billion. Southwest Airlines (LUV) had a market capitalization of $ 28.80 billion, debt of $ 2.70 billion, cash of $ 2.90 billion, and revenues of $ 18.60 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.