since the rate is a weekly basis, the period will also be in a weekly basis, so t = 4, assuming a month to be 4 weeks.
[tex]~~~~~~ \textit{Simple Interest Earned Amount} \\\\ A=P(1+rt)\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{original amount deposited}\dotfill & \$50\\ r=rate\to 5\%\to \frac{5}{100}\dotfill &0.05\\ t=weeks\dotfill &4 \end{cases} \\\\\\ A=50[1+(0.05)(4)]\implies A=50(1.2)\implies A=60[/tex]
