I am trying to take an employees number and balances subtype to subtract the balance for that subtype from the next line.

For example:

Employee Name Subtype Units Used
Employee A 25 1040 0
Employee A 30 240 0
Employee A 30 220 20


Employee A 30 210 10
Employee B 25 1040 0
Employee B 30 240 0
Employee B 30 200 40

The data stacks and I want to be able use the employee's name, then look at the subtype "30" and subtract from the previous line.