Answer:
A. 35
Explanation:
a || b .....(given)
line c is their transversal.
-> x° + (3x + 40)° = 180° (Interior angles on the same side of transversal)
-> (3x + 40 + x)° = 180°
-> (4x + 40)° = 180°
-> 4x + 40 = 180
-> 4x = 180 - 40
-> 4x = 140
-> x = 140/4
-> x = 35