Rollup of Sum Fields

[Ringthebells86]

I am using Airtable to track hours worked versus workable hours in a month to try and calculate how much overtime there was in a given month. The table below is correctly doing what I want where # Hours Worked is the number of hours a person logged in a given month for different tasks. Total Hours is work days including holidays, Total Work Hours is work days not including holidays. And Hours Worked - Holidays is self explanatory (we don't want to count holiday time towards comp time). 

Looking at the below screenshot, the comp time would be 1 hour (161-160). The problem is that I don't think you can make a formula that can do math with the summary types. I was trying to do rollups in a different tab but it wasn't working. In excel I would do a SUMIF function where the criteria is that Month = Sep 2023 and Resource = X and have it sum total work hours and another one summing hours worked - holiday so I can subtract them.

I'm trying to do this by resource by month. Does anyone know a way to subtract the sum of columns or some other way to do this?

[Databaser]

Is "Sep 2023" data from a linked field that you are using to group here? So a record "Sep 2023" from another table? If yes, you can go to that table and add a rollup field there to rollup the working hours (etc) fields there per month/year.  

[Ringthebells86]

That works for total hours worked in September but I need it to roll up the hours in September by person and also by task. Is it possible to do a roll up grouped by something else? Or would I need to make separate columns/views that add extra criteria to the rollup?

I'm basically looking for a SUMIF function like excel does where it'll sum (or in this case rollup) the hours based on month and person, but I don't know if Airtable can do anything like that