\[1,5\sqrt[6]{\frac{1}{64}} - \sqrt[4]{\frac{81}{625}} = 1,5 \cdot \frac{1}{2} - \frac{3}{5} =\]
\[= \frac{15}{20} - \frac{3}{5} = \frac{3^{\backslash 5}}{4} - \frac{3^{\backslash 4}}{5} =\]
\[= \frac{15 - 12}{20} = \frac{3}{20}\]