[tex]\bf \qquad \qquad \textit{Future Value of an ordinary annuity}
\\\\
A=d\left[ \cfrac{\left( 1+\frac{r}{n} \right)^{nt}-1}{\frac{r}{n}} \right]
\\\\\\
\qquad
\begin{cases}
A=
\begin{array}{llll}
\textit{compounded amount}
\end{array}\to &
\begin{array}{llll}
40,000
\end{array}\\
d=\textit{periodic deposits}\\
r=rate\to 4.8\%\to \frac{4.8}{100}\to &0.048\\
n=
\begin{array}{llll}
\textit{times it compounds per year}\\
\textit{is monthly, thus 12}
\end{array}\to &12\\
t=years\to &18
\end{cases}[/tex]
solve for "d"
