Ответ:
\[\frac{a + x}{6} = 11;\ \ \ \ \ \ \ \ \ \ \frac{a}{5} = 12\]
\[a = 66 - x\ \ \ \ \ \ \ \ \ \ \ a = 60\]
\[66 - x = 60\]
\[x = 6\]
\[Ответ:x = 6.\]
\[\frac{a + x}{6} = 11;\ \ \ \ \ \ \ \ \ \ \frac{a}{5} = 12\]
\[a = 66 - x\ \ \ \ \ \ \ \ \ \ \ a = 60\]
\[66 - x = 60\]
\[x = 6\]
\[Ответ:x = 6.\]