i need help im stuck on this question please help me heres the input 25 and the output is 15

Of course! I'd be happy to help you with your question.

To understand how the input of 25 gives an output of 15, I need a bit more context. Could you please provide me with some additional information? Specifically, I would like to know what process or calculation is being used to derive the output of 15 from the input of 25.