Question 1:
The answer is D, vertical angles.
Vertical angles means that 2 angles are opposite from each other for 2 lines overlapping each other. The value of those 2 angles should be same.
Question 2:
If 2 lines are Perpendicular to each other, their angle should add up to 90°(i.e. Right angle)
So, this means that angle ABC and angle CBD should add up to 90°.
Before finding the value of angle CBD, we have to find the value of x.
4x = 90° - 30°
4x = 60°
X = 15°
Therefore, just substitute x = 15° into angle CBD.
Angle CBD = 4 x 15°
=60°
