Answer:
The answer for "?" is z+1.
Step-by-step explanation: In order to solve this I recommend comparing the two equations and expanding them as much as possible, like so.
Once you have the equations expanded to their maximum you can see what was added to the right side of the equation and what you need to add to the numerator in this case to make the two equations equal.
*Note: You can also check the solution by plugging in a number for z and checking to see that both side equal. For example if z = 3.
So, z+1 is the answer.