\[\boxed{\text{4\ (4).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ \frac{a^{2} - 1}{a - 5}\ \]
\[при\ a = - 4:\]
\[\frac{( - 4)^{2} - 1}{- 4 - 5} = \frac{16 - 1}{- 9} = - \frac{15}{9} =\]
\[= - 1\frac{6}{9} = - 1\frac{2}{3}.\]
\[2)\ \frac{x + 3}{y} - \frac{y}{x + 2}\ \]
\[при\ x = - 5;\ \ y = 6:\]
\[\frac{- 5 + 3}{6} - \frac{6}{- 5 + 2} = \frac{- 2}{6} - \frac{6}{- 3} =\]
\[= - \frac{1}{3} + 2 = 1\frac{2}{3}.\]