In January $2022,$ United Airlines $($UAL$)$ had a market capitalization of $$14\mathrm{.}43$ billion, debt of $$32\mathrm{.}44$ billion, and cash of $$18\mathrm{.}58$ billion. United Airlines had revenues of $$25\mathrm{.}07$ billion. Southwest Airlines $($LUV$)$ had a market capitalization of $$26\mathrm{.}52$ billion, debt of $$11\mathrm{.}82$ billion, cash of $$15\mathrm{.}41$ billion, and revenues of $$15\mathrm{.}64$ 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.