Get the difference between 2 dates and then average it by category

I have a table with 3 columns Entity, Start_Date and End_Date as follows: Entity Start End A 1/1/2024 1/31/2024 A 1/28/2024 2/12/2024 A 5/1/2024 6/5/2024 B 7/31/2024 8/27/20...