Answer:
C
Explanation:
given lines a and b are parallel , then
5x and 4x are same- side interior angles and sum to 180°
sum the 2 angles, equate to 180 and solve for x
5x + 4x = 180 , that is
9x = 180 ( divide both sides by 9 )
x = 20
Then
5x = 5 × 20 = 100°
4x = 4 × 20 = 80°
The angle pair are 100° and 80°