\[\boxed{\text{5.\ 26}}\]
\[\textbf{а)}\ 7,646 - (6,9 - 2,054) =\]
\[= 7,646 - 6,9 + 2,054 =\]
\[= 9,7 - 6,9 = 0,8\]
\[\textbf{б)}\ 4,17 + (9,182 - 4,17) =\]
\[= 4,17 + 9,182 - 4,17 = 9,182\]
\[\textbf{в)}\ \frac{4}{9} + \left( \frac{1}{9} - \frac{2}{3} \right) = \frac{4}{9} + \frac{1}{9} - \frac{6}{9} =\]
\[= \frac{5}{9} - \frac{6}{9} = - \frac{1}{9}\]
\[\textbf{г)}\ \left( 3\frac{5}{8} + 2\frac{2}{13} \right) - \left( 2\frac{7}{8} + 1\frac{2}{13} \right) =\]
\[= 3\frac{5}{8} + 2\frac{2}{13} - 2\frac{7}{8} - 1\frac{2}{13} =\]
\[= \left( 2\frac{13}{8} - 2\frac{7}{8} \right) + \left( 2\frac{2}{13} - 1\frac{2}{13} \right) =\]
\[= \frac{6}{8} + 1 = \frac{3}{4} + 1 = 1\frac{3}{4}\]
\[\textbf{д)} - \left( 3,69 - 6\frac{2}{13} \right) - \left( 1,31 - 8\frac{11}{13} \right) =\]
\[= - 3,69 + 6\frac{2}{13} - 1,31 + 8\frac{11}{13} =\]
\[= - 5 + 14\frac{13}{13} = - 5 + 15 = 10\]
\[\textbf{е)} - \left( \frac{5}{8} + 2,43 \right) - \left( - 5,93 - \frac{1}{4} \right) =\]
\[= - \frac{5}{8} - 2,43 + 5,93 + \frac{1}{4} =\]
\[= - \left( \frac{5}{8} - \frac{2}{8} \right) + 3,5 = - \frac{3}{8} + 3\frac{1}{2} =\]
\[= 3\frac{4}{8} - \frac{3}{8} = 3\frac{1}{8}\]