\[\boxed{\mathbf{713\ (713).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\textbf{а)}\ \frac{15}{20};\ \frac{4}{16};\ \frac{7}{10};\ \frac{10}{8};\ \frac{3}{7};\ \frac{5}{6}\text{.\ }\]
\[\frac{3}{4} = \frac{15}{20}\]
\[\frac{3}{4} = \frac{12}{16} \Longrightarrow \frac{4}{16} < \frac{12}{16}\]
\[\frac{7}{10} = \frac{14}{20} \Longrightarrow \frac{14}{20} < \frac{15}{20}\]
\[\frac{10}{8} > 1;\ \ \ \frac{3}{4} < 1\]
\[\frac{3}{7} < \frac{3}{4}\]
\[\frac{3}{4} = \frac{9}{12};\ \ \ \ \frac{5}{6} = \frac{10}{12} \Longrightarrow \frac{9}{12} < \frac{10}{12}\]
\[Ответ:\ \frac{10}{8}\ \ и\ \ \frac{5}{6}.\]
\[\textbf{б)}\ \frac{1}{5};\ \frac{6}{9};\ \frac{9}{10};\ \frac{7}{12}.\]
\[\frac{1}{5} < \frac{2}{3}\]
\[\frac{2}{3} = \frac{6}{9}\]
\[\frac{9}{10} > \frac{2}{3}\]
\[\frac{2}{3} = \frac{8}{12} \Longrightarrow \frac{7}{12} < \frac{8}{12}\]
\[Ответ:\frac{1}{5};\ \frac{7}{12}.\]