[tex]\qquad \textit{Amount for Exponential Decay} \\\\ A=P(1 - r)^t\qquad \begin{cases} A=\textit{current amount}\\ P=\textit{initial amount}\dotfill &310\\ r=rate\to 8.9\%\to \frac{8.9}{100}\dotfill &0.089\\ t=\textit{elapsed time}\dotfill &19\\ \end{cases} \\\\\\ A=310(1-0.089)^{19}\implies A=310(0.911)^{19}\implies A\approx 52.8[/tex]
