C ) 131 is the answer
in the upside-vertex (not inverted) triangle, angle to your left hand side would be equal to x (as interior alternate angles) = 68
and the angle to the right would be 180-y= 180-117 = 163 (as linear angles)
so the angle at the vertex = 180 - (68 + 163) =49 (as angles in a triangle sum upto 180)
so the angle mz = 180 - 49 = 131 degrees (as linear pair of angles or angle in a straight line)
