To understand why FormulaOne shows '25' you need to understand the Multi-pass reporting engine of Crystal Reports.
Open CR and hit F1 and search for Multi-pass reporting for more information.
P.S: When you place three formulas referring to the same variable one beside the other, then is no guarantee that they will execute one after the other. So, perhaps in the background, Formulatwo executes first, then maybe FormulaThree and then FormulaOne.
To avoid this we use something called 'EvaluateAfter()' which I used in my 1st example.
And I did tell you that this might be confusing and irrelevant to this thread and that it is best for you to understand how CR works first.
If you're a beginner and taking some classes, I guess you've jumped too many chapters at the moment!
-Abhilash