Question

Given: parallel lines are crossed by a transversal line.

What is the value of x?

80°
90°
100°
180°

Answer 1

x+100=180,
then x=80

Answer 2

The answer is 80°

As, 100°+x = 180° [being co-interior angles] Or, x = 180° - 100°
then, x = 80°