\[\boxed{\text{5.364.}}\]
\[\textbf{а)}\ 35\ :7 = 5\ \]
\[\frac{5}{7} = \frac{5 \cdot 5}{7 \cdot 5} = \frac{25}{35}\text{.\ }\]
\[\textbf{б)}\ 34\ :17 = 2\ \]
\[\frac{6}{17} = \frac{6 \cdot 2}{17 \cdot 2} = \frac{12}{34}\text{.\ }\]
\[\textbf{в)}\ 70\ :14 = 5\ \]
\[\frac{11}{14} = \frac{11 \cdot 5}{14 \cdot 5} = \frac{55}{70}\text{.\ }\]
\[\textbf{г)}\ 57\ :19 = 3\ \]
\[\frac{15}{19} = \frac{15 \cdot 3}{19 \cdot 3} = \frac{45}{57}\text{.\ \ }\]