\[(a - 5)x = 27\]
\[x = \frac{27}{a - 5}\]
\[x = 9:\]
\[(a - 5) \cdot 9 = 27\]
\[a - 5 = 3\]
\[a = 8.\]
\[Уравнение\ имеет\ корень,\ равный\ 9,\ \]
\[при\ a = 8.\]