[tex]~~~~~~ \textit{Simple Interest Earned Amount \underline{in 15 years}} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill & \$400\\ r=rate\to 3\%\to \frac{3}{100}\dotfill &0.03\\ t=years\dotfill &15 \end{cases} \\\\\\ A=400[1+(0.03)(15)]\implies A=400(1.45)\implies A=580 \\\\[-0.35em] ~\dotfill\\\\ ~\hfill y=400(1.03x)~\hfill[/tex]