Sumproduct help
 

Greetings to all
I have 12 distribution areas that are divided into 4 subregions. each. My
spreadsheet is arranged as follows for each area
A13 area director
a14 region1 rep
a15 items bought
a16 items sold
a14:a16 repeats for each sub region

Below the I am trying to total each distribution area bought and sold:
A170=area1 total bought
A171=area1 total sold
A172=area2 total bought
A173= area2total sold
etc through all ditribution areas.

Im thinking I might need to use a combination of sumproduct and mod(row(),x)
but I cant figure out the x part.

Thanks for your help