The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 20.5956\\[1 em]x_2 &= 1.7022+0.9934i\\[1 em]x_3 &= 1.7022-0.9934i \end{aligned} $$Polynomial $ x^3-24x^2+74x-80 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.