I am thinking of a function len() and a dim of 3 variables as  long, you may need to separate column 1 into the 3 variables and do the math that way.  this will take some VBA. L like to see a picture I'm having a hard time visualizing in my mind.

If the calculation is based on the values in column 2 for the two values in column 1, what is the basis for including the values in the calculation? I agree with Juan, a screenshot of your report would be helpful.

Assuming values in column one are something like "Car", "House", "Farm" and values in column two are expenditures for each then probably use a Sum(IIF()) function. Have one for each of the three options and a total.

I think the answer from A Glenn Yesner is what i need, but i am not sure about the syntax.

The 3 values in column 1 (named "Transportmethod) : Car, Bike, Train
Values in column 2 is the cost of the transport metode in column 1 (named "Transportcosts")
I want to calculate the sum of all the costs for Car and Bike, but not Train, but i want the costs for train records to be displayed in the detail lines part of the record

Would the syntax be like : =sum(IIF(Transportmethod = Car or Transportmethod = Bike), Transportcosts)

Assume the table is tblTransportType, fields are Transportmethod and Transportcosts, record source for the report is the table (tblTransportType), group by the field Transportmethod and in the footer of the group put
=Sum(IIf([Transportmethod]="Car",[Transportcosts]))
Then modify it for each of the other groups (Bike, Train). Make sure you limit users that input the data to a list so "Car" is always "Car" and not "Auto" or "Toyota".
You can do it with queries and probably several other ways, this is the first that hit my mind.

Forgot to mention, make
=Sum(IIf([Transportmethod]="Car",[Transportcosts]))
the Control Source for a text box

A Glenn Yesner - thank you very much. Your proposed solution did it.