\[\boxed{\mathbf{3.48}}\]
\[\textbf{а)}\ 1\frac{5}{6}?\frac{6}{11} = 1\]
\[\frac{11}{6} \cdot \frac{6}{11} = 1\]
\[\textbf{б)}\ 3?2\frac{1}{4} = \frac{3}{4}\]
\[3 - 2\frac{1}{4} = \frac{3}{4}\]
\[\textbf{в)}\frac{5}{9}?\frac{7}{9} = \frac{5}{7}\]
\[\frac{5}{9}\ :\frac{7}{9} = \frac{5}{9} \cdot \frac{9}{7} = \frac{5}{7}\]
\[\textbf{г)}\ \frac{5}{14}?0,7 = \frac{1}{4}\]
\[\frac{5}{14} \cdot \frac{7}{10} = \frac{1}{4}\]