Does anyone know how to do this I’m really confused

The size of the unknown angle "x"
The given polygon is a Pentagon so the sum of interior angle will be,
[tex]\large\boxed{Formula: ( n − 2 ) × 180}[/tex]
n means the number of sides
Let's substitute the values according to the formula.
[tex](5-2)×180[/tex]
[tex]=540°[/tex]
Now, we can find the sum of one interior angle.
[tex]\large\boxed{\frac{sum \: of \: interior \: angles}{n}}[/tex]
n means the number of sides.
Let's substitute the values according to the formula.
[tex]x=\frac{540}{5}[/tex]
[tex]\large\boxed{x= 108°}[/tex]
Therefore, the size of the unknown angle "x" is 108°