8. \(\frac{7}{8}\left(\frac{2}{4}+\frac{3}{10}\right)\)

\(\frac{2}{4}=\frac{1}{2}=\frac{5}{10}\).

\(\frac{5}{10}+\frac{3}{10}=\frac{8}{10}=\frac{4}{5}\).

\(\frac{7}{8}\cdot\frac{4}{5}=\frac{7}{10}\).

Ответ: \(\frac{7}{10}\).