\[\boxed{\mathbf{2.}\mathbf{86}}\]
\[0,7 = \frac{7}{10};\ \ \ 0,29 = \frac{29}{100};\ \ \ 0,2 =\]
\[= \frac{2}{10} = \frac{1}{5}.\]
\[\frac{7}{8} = \frac{7 \cdot 125}{8 \cdot 125} = \frac{875}{1000} = 0,875;\]
\[3\frac{1}{2} = 3\frac{5}{10} = 3,5;\]
\[6\frac{12}{25} = 6\frac{48}{100} = 6,48.\]