From the exercise we have
[tex]\begin{gathered} \text{John}=6\frac{1}{2}=6.5 \\ Ben=\frac{John}{2}=\frac{6.5}{2}=3.25 \\ \text{Sara}=4.75 \end{gathered}[/tex][tex]\begin{gathered} \text{TotalDistance=6.5+3.25+4.75} \\ \text{TotalDistance}=14.5\text{miles} \end{gathered}[/tex]