The roots of polynomial $ p(x) $ are:
$$ \begin{aligned}x_1 &= 7\\[1 em]x_2 &= -5 \end{aligned} $$Step 1:
Get rid of fractions by multipling equation by $ \color{blue}{ 9 } $.
$$ \begin{aligned} \frac{10}{9}x^2-\frac{20}{9}x-\frac{350}{9} & = 0 ~~~ / \cdot \color{blue}{ 9 } \\[1 em] 10x^2-20x-350 & = 0 \end{aligned} $$Step 2:
The solutions of $ 10x^2-20x-350 = 0 $ are: $ x = -5 ~ \text{and} ~ x = 7$.
You can use step-by-step quadratic equation solver to see a detailed explanation on how to solve this quadratic equation.