>hi all,
>
>any idea,help how i can make this operatins...
>
>1.date(+,-,/,*)date=duration

date + date means nothing
date - date = duration days
date * date means nothing
date / date means nothing

>
>2.duration(+,-,/,*)date=date

date + duration(days) = date
date - duration(days) = date
date * duration means nothing
date / duration means nothing

>
>3.duration(+,-,/,*)duration=duration

duration + duration = duration
duration + duration = duration
duration * duration = many things
duration / duration = duration ratio

>
>
> thanks.