Answer
See answers below
Work Step by Step
The starting value $a_1$ is $162$. The common ratio $r$ is $\frac{108}{162}=\frac{2}{3}$.
The recursive formula is: $a_1=162; a_n=a_{n-1}.\frac{2}{3}$
The explicit formula is: $a_n=162.(\frac{2}{3})^{n-1}$
