This problem could be two different things:
You could of meant: Evalute 3z when z=9
If thats what you wanted here:
Answer: 27
Explanation: Substitute: 3x9 Calculate the product or quotient: 27
Or what this says, evaluate 3z3z3, z when z=9z=9z, equals, 9
The answer is 108. Because you multiply 3 by 9. which is 27 then you multiply 27 by 4 because thats how many 3zs there are.