well, my name is not Marie, but I hope is ok if I post on it.
[tex] \bf \qquad \textit{Amount for Exponential Decay}
\\\\
A=P(1 - r)^t\qquad
\begin{cases}
A=\textit{accumulated amount}\to &14650\\
P=\textit{initial amount}\to &20000\\
r=rate\to r\%\to \frac{r}{100}\\
t=\textit{elapsed time}\to &2\\
\end{cases} [/tex]
[tex] \bf 14650=20000(1-r)^2\implies \cfrac{14650}{20000}=(1-r)^2\implies \cfrac{293}{400}=(1-r)^2
\\\\\\
\sqrt{\cfrac{293}{400}}=1-r\implies r=1-\sqrt{\cfrac{293}{400}}\implies r=1-\sqrt{0.7325}
\\\\\\
r\approx 0.14413786\implies r\%\approx 0.14413786\cdot 100\implies r\approx\stackrel{\%}{14.41} [/tex]
