How to calculate Total Gross Profit % in SAP

Hi,

I'm concern about how does B1 calculate the total of gross profit %, what is the formula that system use?

Example: I have two items in my sales order, and the gross profit is set to (Profit / Base Price),

Item A :

Base Price = 8.62

Sales Price = 15.60

Qty = 2

Gross Profit = (Sales Price - Base Price) * Qty = (15.60 - 8.62) * 2 = 13.96

Profit % = Gross Profit / Base Price / Qty = (13.96 / 8.62 /2) * 100 = 80.97

Item B:

Base Price = 3.25

Sales Price = 16.25

Qty = 2

Gross Profit = (16.25 - 3.25) * 2 = 26.00

Profit % = (26.00 / 3.25 / 2 ) * 100 = 400.00

Total Profit % for this two items = 168.32

The above calculation I can understand. But how does system calculate the Total Profit % = 168.32

Any one know the formula for Total Profit % ?

Thanks in advance for any help.

Regards,

Muhamad