[tex]\qquad \textit{Amount for Exponential Decay} \\\\ A=P(1 - r)^t\qquad \begin{cases} A=\textit{current amount}\\ P=\textit{initial amount}\dotfill &20000\\ r=rate\to 30\%\to \frac{30}{100}\dotfill &0.3\\ t=\textit{elapsed time}\dotfill &5\\ \end{cases} \\\\\\ A=20000(1 - 0.3)^{5}\implies A=20000(0.7)^5\implies A=3361.4[/tex]