Упростите выражение: 6/(a-1)-10/(a-1)^2:10/(a^2-1)-(2a+2)/(a-1).

\[\frac{6}{a - 1} - \frac{10}{(a - 1)^{2}}\ :\frac{10}{a^{2} - 1} - \frac{2a + 2}{a - 1} =\]

\[= \frac{6 - 2a - 2}{a - 1} - \frac{10}{(a - 1)^{2}} \cdot \frac{a^{2} - 1}{10} =\]

\[= \frac{4 - 2a}{a - 1} - \frac{(a - 1)(a + 1)}{(a - 1)^{2}} =\]

\[= \frac{4 - 2a}{a - 1} - \frac{a + 1}{a - 1} =\]

\[= \frac{4 - 2a - a - 1}{a - 1} = \frac{3 - 3a}{a - 1} =\]

\[= \frac{- 3(a - 1)}{a - 1} = - 3.\]