Dates subtraction

[Ackim Chisha]

Hi Everybody,
Is there a shortcut way to subtract dates say for instance I would like to
be subtracting the current date from the date that the service for  a
particular user expires, say (expiry date -- current date). Or do I have to
write
a specific script for this. Forgive my newbie ignorance.

Kregards,
Ackim.