Treasury bills are currently paying $9$ percent and the inflation rate is $3\mathrm{.}1$ percent. a$.$ What is the approximate real rate of interest? $($Enter your answer as a percent rounded to $2$ decimal places $,$ e$.$g$.,32\mathrm{.}16.)$ b$.$ What is the exact real rate? $($Do not round intermediate calculations and ente answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$