\[\boxed{\text{6.240.}}\]
\[\textbf{а)}\ 4\frac{1}{13} + 4\frac{5}{13} = 8\frac{6}{13}\ \]
\[\textbf{б)}\ 7\frac{3}{5} - 2\frac{2}{5} = 5\frac{1}{5}\ \]
\[\textbf{в)}\ 9\frac{7}{8} - \frac{5}{32} = 9\frac{28}{32} - \frac{5}{32} = 9\frac{23}{32}\]
\[\textbf{г)}\ \frac{6}{12} + 8\frac{1}{18} = \frac{1}{2} + 8\frac{1}{18} =\]
\[= \frac{9}{18} + 8\frac{1}{18} = 8\frac{10}{18} = 8\frac{5}{9}\ \]