\[\boxed{\text{4.\ 233}}\]
\[\textbf{а)} - \frac{3}{17} - \left( - \frac{9}{17} \right) = - \frac{3}{17} + \frac{9}{17} =\]
\[= \frac{6}{17}\]
\[\textbf{б)} - \frac{8}{17} - \left( - \frac{3}{17} \right) = - \frac{8}{17} + \frac{3}{17} =\]
\[= - \frac{5}{17}\]
\[\textbf{в)}\ \frac{7}{13} - \left( - \frac{1}{13} \right) = \frac{7}{13} + \frac{1}{13} =\]
\[= \frac{8}{13}\]
\[\textbf{г)} - \frac{5}{14} - \frac{3}{7} = - \left( \frac{5}{14} + \frac{6}{14} \right) =\]
\[= - \frac{11}{14}\]
\[\textbf{д)}\ \frac{1}{2} - \frac{4}{5} = \frac{5}{10} - \frac{8}{10} = - \frac{3}{10}\]
\[\textbf{е)} - \frac{2}{3} - \left( - \frac{5}{6} \right) = - \frac{4}{6} + \frac{5}{6} = \frac{1}{6}\]
\[\textbf{ж)} - \frac{3}{4} - \left( - \frac{4}{9} \right) = - \frac{27}{36} + \frac{16}{36} =\]
\[= - \frac{11}{36}\]
\[\textbf{з)}\ \frac{3}{8} - \frac{5}{12} = \frac{9}{24} - \frac{10}{24} = - \frac{1}{24}\]