\[2\frac{3}{4} - \left( - 1\frac{1}{2} \right) + \left( - 3\frac{5}{6} \right) =\]
\[= 2\frac{3 \cdot 3}{12} + 1\frac{1 \cdot 6}{12} - 3\frac{5 \cdot 2}{12} =\]
\[= 2\frac{9}{12} + 1\frac{6}{12} - 3\frac{10}{12} = 3\frac{15}{12} - 3\frac{10}{12} = \frac{5}{12}\text{.\ }\]