I'm using tableau public so can't see your workbook right now.
However you can use LOOKUP() function to calculate the variance.
see the screen shot.
I assumed your data like this. If your data is not like that then kindly share the sample data in excel format.
If your data is as per the above screen shot then follow the below screen shot to calculate the variance.
Feel free to ask if you have any query.
Thank you it is helpful.
My data organisation is slightly different.
Short table as per bellow.
Sorry, I am new user, can't find how to attach the file
Year Brand Sales Profit 2015 A 1020 640 2016 A 1350 600
Thank you for Prompt support, Dany
see the attached workbook. I've create separate calc fields to calculate the variance.
attached workbook in version 9.2
while replying to original post you may have option to attached files. see the below screenshot. Once you click on that you will get attach option at right bottom.
Variance.twbx 12.3 KB