We have to estimate how much he expects to make investing $4200 if he should make $12 for every $100.
We can apply the rule of three as:
[tex]\begin{gathered} 100-->12 \\ 4200-->x=4200*\frac{12}{100} \\ x=4200*0.12 \\ x=504 \end{gathered}[/tex]Answer: he expects to make $504.
