Pollution levels in a lake have been modeled by the equation

x $=0\mathrm{.}05+0\mathrm{.}16$e$0\mathrm{.}36$t

where x is the volume of pollutants $($in cubic kilometers$)$ and t is the time $($in years$).$ What is the rate of change of x with respect to time?

x$\text{'}($t$)=$