let's firstly convert the mixed fractions to improper fractions and then get their product.
[tex]\stackrel{mixed}{3\frac{1}{2}}\implies \cfrac{3\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{7}{2}} ~\hfill \stackrel{mixed}{1\frac{3}{7}}\implies \cfrac{1\cdot 7+3}{7}\implies \stackrel{improper}{\cfrac{10}{7}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{7}{2}\cdot \cfrac{10}{7}\implies \cfrac{7}{7}\cdot \cfrac{10}{2}\implies 1\cdot 5\implies 5[/tex]
