\(S-Sam's\ age\\H-Hank's\ age\\\\ \left\{\begin{array}{ccc}\frac{S}{H}=\frac{5}{3}\\S+H=24&\to S=24-H\end{array}\right\\\\substitute\ S=24-H\ to\ \frac{S}{H}=\frac{5}{3}\\\\\frac{24-H}{H}=\frac{5}{3}\\\\cross\ multiply\\\\5H=3(24-H)\\5H=72-3H\\5H+3H=72\\8H=72\ \ \ /:8\\H=9\\\\Answer:Hank\ is\ 9\ years\ old.\)