\[3\frac{1}{10} - 5\frac{7}{90} = \frac{91^{\backslash 3}}{30} - \frac{457}{90} =\]
\[= \frac{273}{90} - \frac{457}{90} = - \frac{184}{90} =\]
\[= - 2\frac{4}{90} = - 2\frac{2}{45}\]