How to substract a number e.g. 20 from a date field

[Alex Agn]

Dear community,

I try to calculate when a project feasibility should start.

I have the total jobsize e.g. 200
-> 10% of Jobsize= the amount of days necessary for the feasibility phase 
--> I created a structure formula column named: FeasibilityJobSize (200*(10/100)) -> Numerical value

-> Additionally I know the deadline of the project e.g. 25/03/2023


Now I want to know when the Feasibility phase needs to finish in order to deliver on time.
Therefore I want to create an additional formula column:
FeasibilityDueDate 

-> 25/03/2023 - FeasibilityJobSize (e.g. 20) 
-> The result I want to obtain is 5/03/2023 (= 25/03/2023 - 20days)

What should my formula (Expr language) look like to obtain this result ? 



Many thanks for your all feedback/support!

[David Niro]

Hello @Alex Agn ,

You will want to use the DATE_SUBTRACT function for this.

It will look something like this:

with feasibility_job_size =
    (200*(10/100)):

DATE_SUBTRACT(deadline,feasibility_job_size,"days")

Please let me know if this helps!

Best,
David