Calculating cells

Hi guys

I am creating a spreadsheet to record staff sick leave etc (see attached) I have to record full days and half days. I have started to do this recording both full days and half days separately in the totals tab. However it would be great if instead of the 2 separate columns in the totals half days automatically added to the one total ie 1 full day and 3 half days recorded as 2.5.

any help would be appreciated.

David