I have a target date field and a target time field. I need to subtract this from the complete date field and complete time field. The result will be either a positive or negative number. How do I do this?

 

I thought I'd simply need to combine the date and time fields and then do simple math ... but I'm not sure how to combine the date and time fields into a single value.

 

Any and all suggestions are appreciated.

 

Thank you.