\[- 5\frac{3}{8} + 4\frac{9}{10} =\]
\[= \ - \left( 5\frac{15}{40} - 4\frac{36}{40} \right) =\]
\[= - \left( 4\frac{55}{40} - 4\frac{36}{40} \right) = - \frac{19}{40}\]