Question 347652
How about if I said find {{{f(z)}}} and by the way {{{z=f(9)}}}. 
What would you do? 
FIrst you'd solve for {{{z}}}. 
Then you'd plug that result into {{{f(z)}}}.
But you're really solving {{{f(z)=f(f(9))}}}.
Try that first and see if it makes sense.