let's firstly convert the mixed fractions to improper fractions and then multiply.
[tex]\bf \stackrel{mixed}{3\frac{1}{4}}\implies \cfrac{3\cdot 4+1}{4}\implies \stackrel{improper}{\cfrac{13}{4}}~\hfill \stackrel{mixed}{1\frac{1}{2}}\implies \cfrac{1\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{3}{2}} \\\\[-0.35em] ~\dotfill\\\\ -\cfrac{13}{4}\times -\cfrac{3}{2}\implies \cfrac{-13\cdot -3}{4\cdot 2}\implies \cfrac{39}{8}\implies 4\frac{7}{8}[/tex]
