1) 30°.
2)60°.
3)90°.
4)None of the choices are correct.

Answer:
ABD is a right triangle. Therefor 30 + 4x = 90.
Solve for x.
4x = 60
x = 15
None of the answers are 15, therefor it is D.
None of the choices are correct.
Given BA and BD are perpendicular, So the angle between them is 90°
<ABD = <CBD + <CBA
90° = 4x° + 30°
60° = 4x°
4x° = <CBD = 60°
Hope it helps, if you've any doubts comment below ;))