Find the value of x in the given regular polygon.

The given polygon is a regular pentagon since it has five equal sides.

We know that each interior angle of a regular polygon $=\frac{\left(n-2\right)\times {180}^0}{n}$

Here, n = 5

Therefore, each interior angle $=\frac{\left(5-2\right)\times {180}^0}{5}={108}^o$

According to the question,

Each interior angle $={\left(9x-18\right)}^o$

$\therefore {\left(9x-18\right)}^o={108}^o$

$\Rightarrow 9x=108+18$

$\Rightarrow 9x=126$

$\Rightarrow x=14$