\[\boxed{\mathbf{728\ (728).}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\textbf{а)}\ 4\ :8 = \frac{4}{8} = \frac{1}{2}\]
\[\textbf{б)}\ 3\ :9 = \frac{3}{9} = \frac{1}{3}\]
\[\textbf{в)}\ 12\ :10 = \frac{12}{10} = \frac{6}{5}\]
\[\textbf{г)}\ 8\ :6 = \frac{8}{6} = \frac{4}{3}\]
\[\textbf{д)}\ 25\ :20 = \frac{25}{20} = \frac{5}{4}\]
\[\textbf{е)}\ 10\ :15 = \frac{10}{15} = \frac{2}{3}\]
\[\textbf{ж)}\ 5\ :25 = \frac{5}{25} = \frac{1}{5}\]
\[\textbf{з)}\ 4\ :16 = \frac{4}{16} = \frac{1}{4}\]