\[(6x - 1)(x + 1) = 20\]
\[6x^{2} - x + 6x - 1 - 20 = 0\]
\[6x^{2} + 5x - 21 = 0\]
\[D = 25 + 504 = 529\]
\[x_{1} = \frac{- 5 + 23}{12} = \frac{18}{12} = \frac{3}{2} = 1,5;\]
\[x_{2} = \frac{- 5 - 23}{12} = - \frac{28}{12} = - \frac{7}{3} =\]
\[= - 2\frac{1}{3}.\]
\[Ответ:\ \ 1,5;\ \ - 2\frac{1}{3}.\]