Solution: Answer is correct in three cases.
When we have a triangle, the sum of measures of angles are 180 degrees. In the three pictures of polygons, we have two triangles in each one. So, the sum of angles would be 360 degrees in all cases.
Case A: We have 85+80+100+x = 360. We isolate X,
X=360-85-80-100
X= 95 degrees.
Case B: We have 72+78+60+x = 360. We isolate X,
X=360-72-78-60
X= 150 degrees.
Case C: We have 90+90+30+x = 360. We isolate X,
X=360-90-90-30
X= 150 degrees.
