well, how much is 4/5 of 3 and 1/4? well, is just their product, thus, firstly, let's change the mixed fraction to "improper" and proceed,
[tex]\bf \stackrel{mixed}{3\frac{1}{4}}\implies \cfrac{3\cdot 4+1}{4}\implies \stackrel{improper}{\cfrac{13}{4}}\\\\
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\cfrac{4}{5}\cdot \cfrac{13}{4}\implies \cfrac{13}{5}\implies 2\frac{3}{5}[/tex]
