Help me

 I have employee form here i have e number filed called total leave .

i have another form in new section here i have date field  start leave and end leaves and another formula filed called days requested i am unable to calculate difference of  then i have to reduce Sunday and Saturday.then i fetched that total leave day from employee form  into leave form now i want to subtract total leave from days and i want to display the result in reaming leave field that is number.

thanks