Time stamp diff in framework manager query subject

[KavitaPrasad]

Hi,

I have a open date (Jan 15, 2013 9:21:00 AM) in this format.
And a close date (Jan 16, 2013 10:05:00 AM) in this format.

I need the difference in hours. ie if the diff is 45 minutes i need it in 0.45 format
and if the diff is 1 hour 45 minutes i need it in 1.45 format.

Can anyone help me to achieve this?

Thanks