Hello folks - would appreciate help with this, please!

I'm setting up a summary sheet to help track housing for a conference.
For each date I have a formula to track the number of rooms, i.e. for
January 7: =COUNTIF('Housing
List'!F:F,"1/07/2005")+B4-(COUNTIF('Housing List'!G:G,"1/07/2005"))

This counts the number of people arriving on the 7th, plus the number
people already arrived prior, minus anyone leaving on the 7th.

So now I need to break it down further, and use that same formula but
only count the single rooms, so the ones with "Single" in column H (and
then I need to do the same with Doubles).

How can I add that extra condition?

And THEN - oh this gets fun - I need to break it down one step further
and count the number of people from a particular group (code is in
column A) who have doubles for a particular night, and then for the
same group the number who have singles.
Please help!! :-)

Christina - Muse of Fire