Answer
(a) $392$
(b) $73$
Work Step by Step
(a) Use the exponential model, $n(t)=n_0e^{rt}$ with $n_0=22, t=24,r=0.12$ for this case.
Thus, $n(24)=22e^{0.12\times24}=391.9\approx392$
(b) For this case, use $r=0.05$, we have $n'(24)=22e^{0.05\times24}=73$