Найдите частное: (3n-9)/(n^2-10n+25):(9-n^2)/(n-5).

\[\frac{3n - 9}{n^{2} - 10n + 25}\ :\frac{9 - n^{2}}{n - 5} =\]

\[= \frac{3n - 9}{n^{2} - 10n + 25} \cdot \frac{n - 5}{9 - n^{2}} =\]

\[= \frac{- 3(3 - n)(n - 5)}{(n - 5)^{2}(3 - n)(3 + n)} =\]

\[= - \frac{3}{(n - 5)(3 + n)} =\]

\[= \frac{3}{(5 - n)(3 + n)}.\]