For a convex polygon with n sides, the sum of interior angles is (n-2)·180°. Thus, the sum of interior angles of a pentagon is (5-2)·180° = 540°.
... x° + 131° + 108° + 107° + 110° = 540°
... x° = 84° . . . . . . subtract 456° from both sides.
The value of x is 84.