[tex]\bf \cfrac{\frac{a}{b}}{\frac{c}{{{ d}}}}\implies \cfrac{a}{b}\cdot \cfrac{{{ d}}}{c}\\\\
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\cfrac{\frac{10}{9}}{\frac{8}{9}}\implies \cfrac{10}{\underline{9}}\cdot \cfrac{\underline{9}}{8}\implies \cfrac{10}{8}\implies \cfrac{5}{4}[/tex]
