\[\boxed{\mathbf{2.465}}\]
\[4\frac{5}{15} + 2\frac{3}{15} = 6\frac{8}{15} = \frac{98}{15}\]
\[4\frac{5}{25} - 1\frac{8}{25} = 3\frac{30}{25} - 1\frac{8}{25} =\]
\[= 2\frac{22}{25} = \frac{72}{25}\]
\[\frac{98}{15}\ :\frac{72}{25} = \frac{98}{15} \cdot \frac{25}{72} = \frac{49 \cdot 5}{3 \cdot 36} =\]
\[= \frac{245}{108} = 2\frac{29}{108}\]
\[\textbf{б)}\ \left( 8\frac{11}{24} - 7\frac{1}{12} \right)\ :\left( 3\frac{1}{4} + 2\frac{1}{8} \right) =\]
\[= \frac{11}{43}\]
\[8\frac{11}{24} - 7\frac{2}{24} = 1\frac{9}{24} = 1\frac{3}{8} = \frac{11}{8}\]
\[3\frac{1}{4} + 2\frac{1}{8} = 3\frac{2}{8} + 2\frac{1}{8} = 5\frac{3}{8} = \frac{43}{8}\]
\[\frac{11}{8}\ :\frac{43}{8} = \frac{11}{8} \cdot \frac{8}{43} = \frac{11}{43}\]