The sum of the inner angles of a polygon with n sides is [tex] 180(n-2) [/tex]
Since your polygon has 6 sides, the sum of its inner angles has to be
[tex] 180(6-2) = 180 \cdot 4 = 720[/tex]
On the other hand, the sum of its inner angles is
[tex] 75+132+113+108+160+x = 588+x [/tex]
And it has to be 720, so we have
[tex]588+x=720 \iff x = 720-588 = 132 [/tex]
