Let's see if I can set this up right...

I have a workbook with three sheets. Sheet2 column A has a list of
geographical abbreviations. Column B has a list of garage addresses. Columns D
through BY (that's 76 columns) has a list of sub-geographical areas in each row
that the garage in Column B is responsible for. Each garage is responsible for
unique sub-geographical areas and there are several garages in each parent
geographical area.
Sheet3 Column B has a list of those same sub-geographical areas. Column C
has the amount of work performed in each sub-geographical area and Column D has
the month in which that work was done.
On Sheet1 I would like to have that same list of garages that appears on
Sheet2 but in columns D through I, I would like to show the amount of work done
by each garage for each month represented on Sheet3. So, if the garage at 123
Main did 12 items in areas ABC, 10 in ABD, and 20 in ABE in the month of August,
I would like column D, which represents August's results, to show the sum of
ABC, ABD, and ABE for the month of August. Column E would contain the results
for September, etc.
I've considered trying to use a SUMIF and AND but can't think of anything
that would work. I've also considered a macro but can't think of anything there
either. Any suggests or help would be greatly appreciated. I'm really stuck.
Thanks!