Not display the table cells after editor

Hello. Please tell me how correctly to display in the cell the sum of two other cells, but at the same time changing the display of the changed version and not the entire amount.
https://snippet.webix.com/favc5f9b

depends on the requirements
try this https://snippet.webix.com/8svlbn3k

Thanks, it’s help me, but i have new problem with this. if user didn’t change cell, cell was empty. Help me pls again. Code Snippet

in this case instead of template I would prefer setting default value to sum in scheme->$init
https://snippet.webix.com/sfhy5i9r
https://docs.webix.com/desktop__data_scheme.html