again, there are 12 months in a year, so 54 months is 54/12 years
[tex]\bf \qquad \textit{Compound Interest Earned Amount}
\\\\
A=P\left(1+\frac{r}{n}\right)^{nt}
\quad
\begin{cases}
A=\textit{accumulated amount}\to &\$9996\\
P=\textit{original amount deposited}\\
r=rate\to 5.1\%\to \frac{5.1}{100}\to &0.051\\
n=
\begin{array}{llll}
\textit{times it compounds per year}\\
\textit{monthly, thus twelve}
\end{array}\to &12\\
t=years\to \frac{54}{12}\to &\frac{9}{2}
\end{cases}[/tex]
[tex]\bf 9996=P\left(1+\frac{0.051}{12}\right)^{12\cdot \frac{9}{2}}\implies \cfrac{9996}{\left(1+\frac{0.051}{12}\right)^{12\cdot \frac{9}{2}}}=P[/tex]
