Looking at my GUI above, my movie application allows one to borrow movies for:

If VCD =3 days
DVD = 2 days
VHS = 4

How can I ensure that if one borrows a VHS for example, the checkout date is increased automatically to 4 days from the day of checkout? And there after I will have an admin form where I want to allow the user to determine the number of days allowed, instead of the default that I have set.

How can I code that?

Thanks.