How to find the current and voltage of this circuit?
Your knows are:


VS = 15 V.
R2 = 1 k&Omega;.


Your unknowns are:


I2.
VZD.
U2 (which should be the same as VZD.


If that's all the information you have been given then you can only solve for U2 and I2 in terms of VZD. You won't be able to give a numerical answer as in the case of U1 and I1. 

Are you sure that you have supplied all the information given?