Multi row formula Subtraction

[koreyfras]

I am struggling to get a rolling subtraction in Alteryx for column 'Volume Type I'. I am trying to take the value from 'Volume Type 1' (starting at 3000) and subtract it -100 into a new column while also then taking the new value from the previous row and doing a rolling previous row - 100. In Excel this is obviously easy because I could just drag and copy the formula down, but I am having trouble replicating using the multi row formula tool in Alteryx. Thanks!

Row	Volume Type 1	Type 1 Usage in Gallons	Usage (New Column)
1	3000	100	Row 1 Volume Type 1 (3000) - 100 = 2900
2	3000	100	Row 1 Usage (2900) - 100 = 2800
3	3000	100	Row 2 Usage (2800) - 100 = 2700
4	3000	100	Row 3 Usage (2700) - 100 = 2600
5	3000	100	Row 4 Usage (2600) - 100 = 2500

[griffinwelsh · Accepted solution]

@koreyfras see the attached solution

[koreyfras]

Thank you! This is exactly what I needed, but now I am having problems when I'm trying to apply it to a bigger subset of data. 

I have multiple cities within the data set, and each has a different starting amount for Volume. Is there a way to get it to basically start over the calculation with each new city? See the table below for what I am hoping to replicate. I've attached the workflow and a screenshot. 

City	Volume Type I	Type I Usage in Gallons	Usage
AMA	6000	100	5900
AMA	6000	100	5800
AUS	3000	100	2900
AUS	3000	100	2800