\[\boxed{\text{4.\ 211}}\]
\[\textbf{а)} - 26 + ( - 17) = - 43\]
\[\textbf{б)} - 4,8 + ( - 5,7) = - 10,5\]
\[\textbf{в)} - 3\frac{4}{7} + \left( - 4\frac{1}{7} \right) = - 7\frac{5}{7}\]
\[\textbf{г)} - \frac{5}{9} + \left( - \frac{1}{3} \right) = - \left( \frac{5}{9} + \frac{3}{9} \right) =\]
\[= - \frac{8}{9}\]
\[\textbf{д)} - 0,75 + \left( - \frac{1}{4} \right) =\]
\[= - 0,75 + ( - 0,25) = - 1\]
\[\textbf{е)} - 1 + \left( - \frac{1}{11} \right) = - 1\frac{1}{11}\ \]
\[\textbf{ж)} - 0,4 + \left( - \frac{1}{30} \right) =\]
\[= - \frac{2}{5} + \left( - \frac{1}{30} \right) =\]
\[= - \left( \frac{12}{30} + \frac{1}{30} \right) = - \frac{13}{30}\]
\[\textbf{з)}\ \frac{9}{13} + 2 + \left( - \frac{9}{13} \right) = 2\]
\[\textbf{и)} - 26 + \left( - 20\frac{17}{19} \right) = - 46\frac{17}{19}\]