[tex]\bf \qquad \textit{Amount for Exponential Decay}
\\\\
A=P(1 - r)^t\qquad
\begin{cases}
A=\textit{accumulated amount}\\
P=\textit{initial amount}\to &15000\\
r=rate\to 20\%\to \frac{20}{100}\to &0.20\\
t=\textit{elapsed time}\to &3\\
\end{cases}
\\\\\\
A=15000(1-0.20)^3\implies A=15000(0.80)^3[/tex]
