Could someone please solve for z.
We know all the variables apart from z.
Well, this is the best I can make out from how you have the original problem written... learning to write this stuff in TEX on here can be helpful
Is this the correct problem?
Btw, I don't think this belongs in this section... this really feels like more of a basic algebra question than abstract algebra or whatever.
But I'll help anyway since it's here.
What work have you been able to do yourself so far?