[tex]\bf ~~~~~~ \textit{Compound Interest Earned Amount}
\\\\
A=P\left(1+\frac{r}{n}\right)^{nt}
\quad
\begin{cases}
A=\textit{accumulated amount}\\
P=\textit{original amount deposited}\to &\$18000\\
r=rate\to 9\%\to \frac{9}{100}\to &0.09\\
n=
\begin{array}{llll}
\textit{times it compounds per year}\\
\textit{semi-annual, thus twice}
\end{array}\to &2\\
t=years\to &6
\end{cases}
\\\\\\
A=18000\left(1+\frac{0.09}{2}\right)^{2\cdot 6}\implies A=18000(1.045)^{12}[/tex]
