\[\boxed{\mathbf{Проверочная\ работа\ №3.\ Повторение:обыкновенные\ дроби}}\]
\[\boxed{\mathbf{1.}}\]
\[3\frac{7}{250}.\]
\[\boxed{\mathbf{2.}}\]
\[\frac{23}{5} = 4\frac{3}{5}.\]
\[\boxed{\mathbf{3.}}\]
\[2\frac{1}{7} = \frac{15}{7}.\]
\[\boxed{\mathbf{4.}}\]
\[\frac{1}{6} \cdot \frac{2}{5} = \frac{1}{3 \cdot 5} = \frac{1}{15}.\]
\[\boxed{\mathbf{5.}}\]
\[\frac{1}{6}\ :\frac{2}{5} = \frac{1}{6} \cdot \frac{5}{2} = \frac{5}{12}.\]
\[\boxed{\mathbf{6.}}\]
\[\frac{1}{3} - \frac{1}{9} = \frac{3}{9} - \frac{1}{9} = \frac{2}{9}.\]
\[\boxed{\mathbf{7.}}\]
\[Да.\]
\[1\frac{2}{5} = \frac{7}{5} \rightarrow \frac{5}{7}.\]
\[\boxed{\mathbf{8.}}\]
\[Нет.\]
\[1\frac{3}{8} + 2\frac{3}{4} = 1\frac{3}{8} + 2\frac{6}{8} = 3\frac{9}{8} = 4\frac{1}{8}.\]