\[\boxed{\text{6.20.}}\]
\[\textbf{а)}\ 8\frac{6}{7} < 6\frac{2}{7};\ \]
\[\textbf{б)}\ 8\frac{3}{11} > 7\frac{10}{11};\ \]
\[\textbf{в)}\ 8\frac{5}{9} < \frac{79}{9} = 8\frac{7}{9};\ \]
\[\textbf{г)}\ 3\frac{3}{4}\ м > 3,85\ см;\ \]
\[\textbf{д)}\ 11\frac{7}{13} = \frac{150}{13};\ \]
\[\textbf{е)}\ 7\frac{2}{5}\ кг < 7\ 400\ кг.\ \ \ \]