if we change 2½ years to an improper fraction, that'd be 5/2 years.
[tex] \bf ~~~~~~ \textit{Simple Interest Earned Amount}\\\\A=P(1+rt)\qquad \begin{cases}A=\textit{accumulated amount}\\P=\textit{original amount deposited}\to& \$850\\r=rate\to 2\%\to \frac{2}{100}\to &0.02\\t=years\to &\frac{5}{2}\end{cases}\\\\\\A=850\left( 1+0.02\cdot \cfrac{5}{2} \right)\implies A=850(1.05)\implies A=892.5 [/tex]
