[tex]\bf ~~~~~~ \textit{Simple Interest Earned Amount}
\\\\
A=P(1+rt)\qquad
\begin{cases}
A=\textit{accumulated amount}\to &\$678.50\\
P=\textit{original amount deposited}\\
r=rate\to 15\%\to \frac{15}{100}\to &0.15\\
t=years\to &1
\end{cases}
\\\\\\
678.50=P(1+0.15\cdot 1)\implies 678.50=P(1.15)\implies \cfrac{678.50}{1.15}=P[/tex]
