Hey all I need some help re-arranging this equation so I can find z here it is:

also is w^2/wn^2 the same as (w/wn)^2? so I could replace w^2/wn^2 with say r^2?

x= (w^2/wn^2) / (sqrt( {1-w^2/wn^2}^2 + {2*z*w/wn}^2))

So I have the value for x and I need to find the value of z. I have had a couple of goes at it and I am honestly not sure if what I am doing is right or not.

Thanks for any and all assistance in advance!