Formula for SUM minus a particular value

Hi everyone, I am very new to Alteryx. I am stuck here and could not find a proper solution.

Each value in the Delta column is the sum of the previous two months and the current month minus the target value. How can I do this in Alteryx?

Thanks

Datasets

Accepted answers

Use a running total tool for the sum, then it's an easy formula to take away the target value.

This can be achieved with the help of Multi-row formula tool.

([GP Billing]+[Row-1:GP Billing]+[Row-2:GP Billing])-[Target]

Many thanks

Shanker V

I tried this and it does work until the 3rd month. I have values till December. what do I do then?

Please see the attached screenshot, it will help.

([GP Billing]+[Row-1:GP Billing]+[Row-2:GP Billing])-[Target]

Input was:

Output post run,

Many thanks

Shanker V

Use a running total tool for the sum, then it's an easy formula to take away the target value.

This worked. Thank you so much, Christina. Have a great day