The root of polynomial $ p(x) $ is:
$$ \begin{aligned}x &= \dfrac{ 7 }{ 4 } \end{aligned} $$Step 1:
Get rid of fractions by multipling equation by $ \color{blue}{ 2 } $.
$$ \begin{aligned} \frac{7}{2}-2x & = 0 ~~~ / \cdot \color{blue}{ 2 } \\[1 em] 7-4x & = 0 \end{aligned} $$Step 2:
$$ \begin{aligned} 7-4x & = 0 \\[1 em] -4 \cdot x & = -7 \\[1 em] x & = - \frac{ 7 }{ -4 } \\[1 em] x & = \frac{ 7 }{ 4 } \end{aligned} $$