Calculate summary field that is grouped

[question911]

I have created a report that is grouped by a "Region" field(North, South, East, West). I have also created a SUM field based on "Sales" field. The detailed records in my group are summing Sales by Regions. My report looks like this when I run it:

Region Sales
East $10,000,000
North $15,000,000
South $30,000,000
West $60,000,000

But now, I would like to some how create a formula that will allow me to calculate North Region's summarized sales to East Region's summarized sales by either through subtraction or addition. Does anyone know how I can accomplish this task?

 

[synapsevampire]

What does "that will allow me to calculate North Region's summarized sales to East Region's summarized sales by either through subtraction or addition." mean?

Are you looking to subtract one from the other, add them, or?

Post expected output, the descriptive doesn't make sense to this befuddled old mind.

-k