Answer
You need to simplify the function first until the exponent turns into a plain x. Step 1 Leave 1/3 alone that is the a value, initial value. You are looking for the base
Step 2 Deal with the parenthesis. Factor 24 and you will get 2 and the cube of 3.
Step 3 Separate the exponent (2) (x)
Step 4 Now square each term inside the parenthesis
2 squared and cube of 3 square the 2^2 will be 4, the other expression means cube of 3 times cube of 3 and that's cube of 9
Step 5 Your base should be (4 cube of 9)