A$.$ The function bellow decreases logarithmically

$F(t)=245-0\mathrm{.}75lnt,t>0,$

where $F(t)$ is measured in grams, and $t$ is measured in hours.

a$)$ Find the equation that describes the growth rate of the function $F(t)$ with respect to time $t.$ Specify units.

b$)$ When time goes on$,$ what is the growth rate of the function $F(t)?$ What it tells you about the behavior of the function $F(t)?$