\[\boxed{\mathbf{812\ (812)}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\textbf{а)}\ 2\frac{1}{4} + 2\frac{1}{2} + 3\frac{1}{4} + 3\frac{1}{2} + 4\frac{1}{4} + 4\frac{1}{2} + 5\frac{1}{4} + 5\frac{1}{2} =\]
\[= \left( 2\frac{1}{4} + 3\frac{1}{4} + 4\frac{1}{4} + 5\frac{1}{4} \right) + \left( 2\frac{1}{2} + 3\frac{1}{2} + 4\frac{1}{2} + 5\frac{1}{2} \right) = 14 + \frac{4}{4} + 14 + \frac{4}{2} =\]
\[= 28 + 1 + 2 = 31\]
\[\textbf{б)}\ 1\frac{1}{3} + 4\frac{1}{6} + 1\frac{3}{4} + 2\frac{2}{3} + 3\frac{1}{4} =\]
\[= \left( 1\frac{1}{3} + 2\frac{2}{3} \right) + \left( 1\frac{3}{4} + 3\frac{1}{4} \right) + 4\frac{1}{6} = 3 + \frac{3}{3} + 4 + \frac{4}{4} + 4\frac{1}{6} =\]
\[= 11\frac{1}{6} + 1 + 1 = 13\frac{1}{6}.\]