Question

Anybody have a real answer for the question?

Answer 1

based on the "tangent-chord angle theorem", since the arc made by that chord is 168°, the angle enclosed by both the chord and the arc is half that, namely ∡x is 168/2.

now, notice, ∡y and ∡x are "linear angles", therefore

x + y = 180

y = 180 - x.