Storing a result and recalling for the next operation

Hi there,

I have a formula operation whereby I subtract two numbers (e.g. amount owed and amount paid) related an attribute (e.g. customer), and the result is either positive or negative.

I would like to carry over and access this result for the next operation under the same attribute.

Would Make be the best tool to accomplish this? What other methods can be employed to accomplish this?

Thanks in advance.