Have to calculate working hours excluding Weekends,Holidays and NON Working Hours

Hi everybody

Saying that I'm a bit stuck would be an understatement, sooooo I would realy apreciate if someone could help me out on this one.

I need to calculate the time it take a staff member to do a task problem is that a task may take several days to complete, soooooo calculating the time should'nt be a problem or so I thought.

Until I noticed that my simple sum formula was working so well that it was even including weekends holidays and non working hours, BRILLIANT!!!

If anyone could assist me with removing the weekends, holidays and non working hours I would realy appreciate it.

Im currently ussing Excel 2010.

D4=Time Started (Format yyyy/mm/dd hh:mm)
E4=Time End (Format yyyy/mm/dd hh:mm)
F4=Answer (Format [h]:mm)

Working hours are from 07:00 to 17:00

If there is a way to avoid VBA it would be great as I have no idea how to use it. If not I will have to learn how to use it very quickly.

Thank you

Don't know if there is a way to learn VBA very quickly, but can you upload a sample of your spreadsheet?