[tex]3 {x}^{2} - 31x - 60 = 0 \\ a = 3 \\ b = - 31  \\ c =  - 60\\ D =  {b}^{2}  - 4ac = ( - 31) {}^{2} - 4 \times 3 \times ( - 60) = \\ = 961 + 720 = 1681 \: \: ( \sqrt{D} = 41) \\ x_{1} = \frac{31 - 41}{2 \times 3} = - \frac{10}{6} = - \frac{5}{3} = - 1 \frac{2}{3} \\ x_{2} = \frac{31 + 41}{2 \times 3} = \frac{72}{6} = 12[/tex]