\[\boxed{\mathbf{3.1}}\]
Пояснение.
Решение.
\[\frac{113}{5} = \frac{226}{10}\]
\[\frac{21}{30} = \frac{7}{10}\]
\[11,3\ :\frac{1}{2} = \frac{113}{10} \cdot 2 = \frac{113}{5}\]
\[\frac{6,78}{0,3} = \frac{678}{30} = \frac{226}{10}\]
\[5\frac{2}{5}\ :7,4 = \frac{27}{5}\ :\frac{74}{10} = \frac{27}{5}\ :\frac{37}{5} =\]
\[= \frac{27}{5} \cdot \frac{5}{37} = \frac{27}{37}\]
\[\frac{0,55}{0,77} = \frac{55}{77} = \frac{5}{7}\]
\[Тогда:\]
\[\frac{113}{5} = 11,3\ :\frac{1}{2} = 6,78\ :0,3.\]