The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= -0.7093\\[1 em]x_2 &= 0.1832+0.6076i\\[1 em]x_3 &= 0.1832-0.6076i \end{aligned} $$Polynomial $ 70x^3+24x^2+10x+20 $ has no rational roots that can be found using Rational Root Test, so the roots were found using qubic formulas.