$22$ m$?$ Suppose a sample of a certain substance decayed to $\backslash (69\mathrm{.}4\backslash \%\backslash )$ of its original amount after $300$ days. $($Round your answers to two decimal places.$)$

$($a$)$ What is the half$-$life $($in days$)$ of this substance?days

$($b$)$ How long would it take the sample to decay to one$-$third of its original amount?

days