The root of polynomial $ p(x) $ is:
$$ \begin{aligned}x &= \dfrac{ 4 }{ 5 } \end{aligned} $$Step 1:
Combine like terms:
$$ \color{blue}{x} + \color{blue}{9x} -8 = \color{blue}{10x} -8 $$Step 2:
$$ \begin{aligned} 10x-8 & = 0 \\[1 em] 10 \cdot x & = 8 \\[1 em] x & = \frac{ 8 }{ 10 } \\[1 em] x & = \frac{ 8 : 2 }{ 10 : 2} \\[1 em] x & = \frac{ 4 }{ 5 } \end{aligned} $$