\[\boxed{\mathbf{3.113}}\]
Пояснение.
Решение.
\[\textbf{а)}\ 27\ :3\ и\ 72\ :8\]
\[\frac{27}{3} = \frac{72}{8};\ \frac{3}{27} = \frac{8}{72};\ \ \ \frac{3}{8} =\]
\[= \frac{27}{72};\ \frac{8}{3} = \frac{72}{27}.\]
\[Здесь\ скорее\ всего\ опечатка,\ 9\ \]
\[заменим\ на\ 8.\]
\[\textbf{б)}\ 1,02\ :0,34\ и\ 7,5\ :2,5\]
\[\frac{102}{34} = \frac{81}{27};\ \frac{34}{102} = \frac{27}{81};\ \frac{102}{34} =\]
\[= \frac{75}{25};\ \frac{34}{102} = \frac{25}{75}.\]
\[\textbf{в)}\ 3,6 \cdot 36 = 5,4 \cdot 24\]
\[\frac{3,6}{5,4} = \frac{24}{36};\ \frac{5,4}{3,6} = \frac{36}{24};\ \frac{24}{3,6} = \frac{36}{5,4};\]
\[\ \frac{3,6}{24} = \frac{5,4}{36}.\]
\[\textbf{г)}\ 0,8 \cdot 1,17 = 5,2 \cdot 0,18\]
\[\frac{0,8}{5,2} = \frac{0,18}{1,17};\ \frac{8}{52} = \frac{18}{117};\ \frac{52}{8} =\]
\[= \frac{117}{18};\ \frac{117}{52} = \frac{18}{8}.\]