Julio cubes a number then takes the cube root of the result. he ends up with 20. what number did julio start with

Let us say that the number is x.

So the first step that Julio do is to cube the number so that:

x^3

Then the next he did was take cube root of the number, so that:

(x^3)^(1/3)

Solving this would result in:

x^(3/3) = x^1 = x

Since he ends up with 20, therefore:

x = 20

Julio started and ended with the same number which is 20.