\[(x - 7)^{2} = (9 - x)^{2}\]
\[x^{2} - 14x + 49 = 81 - 18x + x^{2}\]
\[- 14x + 18x = 81 - 49\]
\[4x = 32\]
\[x = 32\ :8\]
\[x = 4.\]
\[Ответ:x = 4.\]