ANSWER
A) 540º
B) x = 121º
Step-by-step explanation
PART A
The sum of the interior angles of a polygon is:
![(n-2)\cdot180](https://img.qammunity.org/2023/formulas/mathematics/college/upwuhj3ofuk9ltsljbscid1v15el6t6rmv.png)
Where n is the number of sides of the polygon.
This polygon has 5 sides, so the sum of its interior angles must be:
![(5-2)\cdot180=3\cdot180=540º](https://img.qammunity.org/2023/formulas/mathematics/high-school/9nr8laqj4s104uk3xj34vrxg630aznr3kg.png)
PART B
Now that we know the sum of the interior angles we can find x:
![x+87+92+135+105=540](https://img.qammunity.org/2023/formulas/mathematics/high-school/4mxca76bpnliajd91lcf6258fk3f4z1j5y.png)
Solving for x:
![\begin{gathered} x+419=540 \\ x=540-419 \\ x=121º \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/n1g9dxq0v235v3w03nmek91f9s7ilnwjpw.png)