The sum of the exterior angles is 360 deg. Each interior angle is supplementary to its corresponding exterior angle, so
\((180-x)^\circ+(180-x-1)^\circ+(180-x-2)^\circ+(180-x-3)^\circ+(180-x-4)^\circ+(180-x-5)^\circ=(1065-6x)^\circ=360^\circ\)
So you have
\(1065-6x=360\implies 6x=705\implies x=\dfrac{235}2=117.5\)
