In early 2018, United Airlines (UAL) had a market capitalization of \($25.14\) billion, debt of \($12.73\) billion, and cash of \($5.59\) billion. United also had annual revenues of \($38.72\) billion.

Southwest Airlines (LUV) had a market capitalization of \($28.53\) billion, debt of \($2.24\) billion, cash of \($3.51\) billion, and annual revenues of \($18.25\) 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.