Subitems and how to use them in a different columne

Hi to all the experienced users in the group :slight_smile:
How can I manage to bring the sum of the 2 subitems ($30) to the columne of the costs, so that i do not miss it in the calculation of the total sum? I am not able to figure it out … please advise. Thank you a lot! Or am I still thinking too much in excel terms …