Answer
x = 20°
Step-by-step explanation
Using the concept of alternating angles, we will see that when the two lines A and B are parallel to each other,
Angle 2 = Angle 3
Angle 2 = (3x - 10)°
Angle 3 = (x + 30)°
Angle 2 = Angle 3
3x - 10° = x + 30°
3x - x = 30° + 10°
2x = 40°
Divide both sides by 2
(2x/2) = (40°/2)
x = 20°
Hope this Helps!!!