posted by Sammy .
line BC is one side of a regular n-gon. The sides next to line BC are extended to meet at W. Find the measure of angle W in terms of n
That's a triangle. Use the facts about the relationships between the angles.
If the ngon is regular, then all sides are equal, and all angles are equal. In this case, n=3
Total sum interior angles = (n-2)180
angle W= totalsum/n