\[b - \frac{5}{6}b + \frac{1}{4}b = b\left( 1 - \frac{5}{6} + \frac{1}{4} \right) =\]
\[= b\left( \frac{6}{6} - \frac{5}{6} + \frac{1}{4} \right) = b\left( \frac{1^{\backslash 2}}{6} + \frac{1^{\backslash 3}}{4} \right) =\]
\[= b\left( \frac{2 + 3}{12} \right) = \frac{5}{12}b\]
\[при\ b = 4\frac{4}{5}:\]
\[\frac{5}{12} \cdot 4\frac{4}{5} = \frac{5}{12} \cdot \frac{24}{5} = \frac{24}{12} = 2.\]
\[Ответ:2.\]