namely how many times does 4/5 go into 28⅘, well is just their quotient.
let's firstly convert the mixed fraction to improper, and then divide.
[tex] \bf \stackrel{mixed}{28\frac{4}{5}}\implies \cfrac{28\cdot 5+4}{5}\implies \stackrel{improper}{\cfrac{144}{5}}
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\cfrac{\quad \frac{144}{5}\quad }{\frac{4}{5}}\implies \cfrac{144}{5}\cdot \cfrac{5}{4}\implies \cfrac{144}{4}\cdot \cfrac{5}{5}\implies 36 [/tex]