let's firstly convert the mixed fractions to improper fractions.
[tex]\bf \stackrel{mixed}{3\frac{1}{2}}\implies \cfrac{3\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{7}{2}}~\hfill \stackrel{mixed}{1\frac{1}{3}}\implies \cfrac{1\cdot 3+1}{3}\implies \stackrel{improper}{\cfrac{4}{3}} \\\\[-0.35em] \rule{34em}{0.25pt}[/tex]
[tex]\bf \begin{array}{ccll} miles&hours\\ \cline{1-2}\\ \frac{7}{2}&1\\[0.8em] m&\frac{4}{3} \end{array}\implies \cfrac{~~\frac{7}{2}~~}{m}=\cfrac{~~1~~}{\frac{4}{3}}\implies \cfrac{7}{2m}=\cfrac{3}{4}\implies 28=6m \\\\\\ \cfrac{28}{6}=m\implies \cfrac{14}{3}=m\implies 4\frac{2}{3}=m[/tex]
