Hello everyone.

This is not really a homework but it is very urgent.

I have a Discrete math exam in one day and this problem is giving me so much headache!

(1)

(2)

(3)

I tried finding inverses as well as reducing these three equations to two equations like:

and in both cases the result does not work out for the equation (3).

Could anyone please explain me why it is so and how to do this in a right way?