Custom expression to calculate difference between two periods.

[Emma Hudson]

Hi All

 

I am trying to create an expression to calculate the difference between Q2.2019 and Q3.2019 (in column A of my attached sample data). At the moment I just have a graph which shows the amount per quarter but I need the difference.

 

I'm only just learning how to use custom expressions and I can't get my formula to work properly so any help would be really appreciated.

 

Thanks

 

Em :)