\[\boxed{\mathbf{2.}\mathbf{330}}\]
Пояснение.
Решение.
\[\textbf{а)}\ \frac{2}{5}\ от\ 10:\]
\[10 \cdot \frac{2}{5} = 2 \cdot 2 = 4.\]
\[\textbf{б)}\ \frac{5}{9}\ от\ 36:\]
\[36 \cdot \frac{5}{9} = 4 \cdot 5 = 20.\]
\[\textbf{в)}\ \frac{1}{4}\ от\ \frac{8}{27}:\]
\[\frac{8}{27} \cdot \frac{1}{4} = \frac{8}{27 \cdot 4} = \frac{2}{27}.\]
\[\textbf{г)}\ \frac{5}{6}\ от\ \frac{3}{15}:\]
\[\frac{3}{15} \cdot \frac{5}{6} = \frac{3 \cdot 5}{15 \cdot 6} = \frac{1}{3 \cdot 2} = \frac{1}{6}.\]