let's firstly convert the mixed fraction to improper fraction and then divide.
[tex]\bf \stackrel{mixed}{2\frac{1}{2}}\implies \cfrac{2\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{5}{2}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{5}{2}\div 4\implies \cfrac{5}{2}\div \cfrac{4}{1}\implies \cfrac{5}{2}\cdot \cfrac{1}{4}\implies \cfrac{5}{8}[/tex]
