[tex]\bf \qquad \textit{Amount for Exponential Decay} \\\\ A=P(1 - r)^t\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{initial amount}\dotfill &780\\ r=rate\to 17.1\%\to \frac{17.1}{100}\dotfill &0.171\\ t=\textit{elapsed time}\dotfill &19\ \end{cases} \\\\\\ A=780(1-0.171)^{19}\implies A=780(0.829)^{19}\implies \stackrel{\textit{rounded up}}{A = 22.1}[/tex]
