In January $2022,$ United Airlines $($UAL$)$ had a market capitalization of $$13\mathrm{.}82$ billion, debt of $$32\mathrm{.}79$ billion, and cash of $$17\mathrm{.}91$ billion. United Airlines had revenues of $$24\mathrm{.}89$ billion.

Southwest Airlines $($LUV$)$ had a market capitalization of $$25\mathrm{.}72$ billion, debt of $$11\mathrm{.}85$ billion, cash of $$15\mathrm{.}75$ billion, and revenues of $$16\mathrm{.}27$ 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.