Hi everyone!

I'm really facing problems in when to use modular inverse. I know that you should use it when calculating the following

(*a* / *b*)%*p* = (*a* * *b*^{p - 2})%*p* [Only when *p* is prime]

I know there is a case when subtracting, but I don't know how you do it exactly, can you tell me how? And are there any other cases?

Thanks in advance.