How do I add certain rows and do a calculation?

Hello,

I am new to Tableau still learning. I've tried browsing but couldn't find what I need.

I am trying to do the below calculation,

I want to sum PT,AC,KT,OT and add it to the row per month and add another row which calculates the % of TRADE of the SUM.

I have tried creating a group but couldn't get through.

Any help is appreciated!