Hi guys,
My current formula is AutoSum ( C30 - C50).
This is not what i want.

Part A = C30 to C40
Part B = C41 to C50
Either Part A or Part B should be used instead (and not the sum of Part A + Part B).
If Part A is selected, Part B is void. vice versa.

What i need is...
Subtotal = Either (Sum of C30 to C40) or (Sum of C41 to C50)
How do I go about it?