Respuesta :
[tex]\bf ~~~~~~ \textit{Simple Interest Earned} \\\\ I = Prt\qquad \begin{cases} I=\textit{interest earned}\dotfill&420\\ P=\textit{original amount deposited}\dotfill & \$7000\\ r=rate\to 3\%\to \frac{3}{100}\dotfill &0.03\\ t=years \end{cases} \\\\\\ 420=(7000)(0.03)t\implies \cfrac{420}{(7000)(0.03)}=t\implies 2=t[/tex]
Answer:
he kept the account open for 2 years
Step-by-step explanation: