\[\frac{6x}{1 + 2x} = 5;\ \ \ x \neq - 0,5\]
\[6x = 5(1 + 2x)\]
\[6x = 5 + 10x\]
\[10x - 6x = - 5\]
\[4x = - 5\]
\[x = - \frac{5}{4} = - 1\frac{1}{4}\]
\[x = - 1,25.\]
\[Ответ:x = - 1,25.\]