Formula Calculation QM

Hello.

This is my first time here. I hope you can help me with this please.

For a specific material, plant, group counter and operation, I have several inspection characteristics and two of them are "SPREAD". The requirement is the following:
Inspect 3 characteristics with single results above spread, analyst maximum and minimum values and do a subtraction.
Ex.

0010 = 100

0020 = 120

0030 = 80

0040 = SPREAD

Maximum = 120, Minimum = 80 -> Then calculate = 120 - 80 = 40

The main problem is that these 3 characteristics before each spread are not always at the same place/position but they are always above the "spread". Besides, the maximum and minimum could be at first, second or third position (this numbers are written manually for users in the process).

I was looking for formula parameters and I guess I maybe could use "C9", "CA" or "D0"...

Regards.

March 14 Moderator note: Formula edited to correct it, at user's request.