In $2020,$ Caterpillar Incorporated had about $540$ million shares outstanding. Their book value was $$43\mathrm{.}4$ per share, and the market price was $$99\mathrm{.}70$ per share. The company's balance sheet shows that the company had $$29\mathrm{.}40$ billion of long$-$term debt, which was currently selling near par value.

a$.$ What was Caterpillar's book debt$-$to$-$value ratio?

Note: Do not round intermediate calculations. Enter your answer as a decimal rounded to $2$ decimal places.

b$.$ What was its market debt$-$to$-$value ratio?

Note: Do not round intermediate calculations. Enter your answer as a decimal rounded to $2$ decimal places.

c$.$ Which measure should you use to calculate the company's cost of capital?

$\backslash$table$[[$a$.$ Book debt$-$to$-$value ratio$],[$b$.$ Markeet debt$-$to$-$value ratio$],[$c$.$ Measure$]]$