Excel query / formula problem

I am looking for a macro/formula that will work out the following;
all I really want is to split the time out of the Date and Time, so that End time minus Start time = time open
Trips divide by Time open = trips per hour

Start Date           End Date         &n bsp; Trips
08/11/03 04:59    08/11/03 12:59   332

Any clues, suggestions would be appreciated.

TIA
Steve 

Try this:

The final formula is =D2/(C2*24)