\[\frac{2^{20} \cdot 3^{11}}{72^{6}} = \frac{2^{20} \cdot 3^{11}}{({2³)}^{6} \cdot \left( 3^{2} \right)^{6}} =\]
\[= \frac{2^{20} \cdot 3^{11}}{2^{18} \cdot 3^{12}} = \frac{2^{2}}{3} = \frac{4}{3} = 1\frac{1}{3}\]