Sum the difference in a range of cells if greater than zero

Hi all,

I've created a spreadsheet to track a guest list and RSVPs. I want to account for the four possible scenarios for RSVPs: #guests=#expected, #guests>#expected, #guests<#expected, and no RSVP has been returned.

B C D E
Expected Total Adults Kids
6 6 2 4
2 0
2 3 2 1
3 2 2 0
2 1 1 0

Column C=D+E
I've applied conditional formatting so that cells in column B turn red if #guests<#expected using =$D5>0 and cells turn green if guests have replied that they are attending (regardless of the # of guests) using =AND(ISNUMBER($D5),$D5=0). Any guests who have not replied have column C blank.

I want to calculate a comparison between how many guests were expected and how many are actually attending, based on the RSVPs received so far. In another cell, I can get =IF($D$5=0,"",$C$5-$B$5) to correctly display 0. In this short example, I would expect a sum of 3.
How can I extend this formula over range $D$5:$D$300?

Thanks much!
Kristi

Almost. But I want to include the number in column B in the sum only if the corresponding cell in column D is blank.

Sorry, I posed it incorrectly. I want to include the number in column B in the sum only if the corresponding cell in column D is NOT blank

Got it to work - Thanks!!

@ krjacobs32

Based on your last post it seems that you are satisfied with the solution(s) you've received but you haven't marked your thread as SOLVED. I'll do that for you now but please keep in mind for your future threads that Rule #9 requires you to do that yourself. If your problem has not been solved you can use Thread Tools (located above your first post) and choose "Mark this thread as unsolved".
Thanks.