its $600 into an account that pays simple interest at a rate of 6% per year. How much interest will he be paid

The simple interest formula is given by:
[tex]C=P\cdot r\cdot t[/tex]Where P is the initial investment, r is the annual interest rate, and t is the number of years. From the problem, we identify:
[tex]\begin{gathered} P=600 \\ r=0.06 \\ t=6 \end{gathered}[/tex]Then, in the simple interest formula:
[tex]\begin{gathered} C=600\cdot0.06\cdot6 \\ C=\text{ \$}216 \end{gathered}[/tex]Juan will pay $216 in interest for the first 6 years