\[\boxed{\text{4.\ 242}}\]
\[\textbf{а)}\ \left( - 2\frac{3}{4} - 3\frac{1}{4} \right) + 3,5 =\]
\[= - 6 + 3,5 = - 2,5\]
\[\textbf{б)}\ \left( - 6\frac{4}{9} + 5\frac{5}{18} \right) - 2\frac{1}{2} =\]
\[= \left( - 6\frac{8}{18} + 5\frac{5}{18} \right) - 2\frac{1}{2} =\]
\[= - 1\frac{3}{18} - 2\frac{1}{2} =\]
\[= - 1\frac{3}{18} - 2\frac{9}{18} = - 3\frac{12}{18} = - 3\frac{2}{3}\]
\[\textbf{в)} - 4\frac{3}{5} - \left( 2\frac{5}{6} - 1\frac{1}{3} \right) =\]
\[= - 4\frac{3}{5} - \left( 2\frac{5}{6} - 1\frac{2}{6} \right) =\]
\[= - 4\frac{3}{5} - 1\frac{3}{6} =\]
\[= - 4\frac{3}{5} - 1\frac{1}{2} = - 4,6 - 1,5 =\]
\[= - 6,1\]
\[\textbf{г)} - 4,75 - \left( - 5\frac{1}{2} + 4\frac{1}{4} \right) =\]
\[= - 4,75 - ( - 5,5 + 4,25) =\]
\[= - 4,75 - ( - 1,25) =\]
\[= - 4,75 + 1,25 = - 3,5\]
\[\textbf{д)} - 2\frac{1}{3} + 2\frac{1}{4} + \frac{1}{3} =\]
\[= - 2 + 2\frac{1}{4} = \frac{1}{4}\]
\[\textbf{е)}\ \frac{7}{10} - 3 - \frac{2}{5} + \frac{3}{10} =\]
\[= 1 - 3\frac{2}{5} = - 2\frac{2}{5}\]