Question

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

Answer 1

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 ;))

Answer 2

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.