Looking to automatically put data into a cell dependent on the values of specific other cells in that row

Hello, the goal is to automatically present the value in the “split amount” columns cell to be half the value of the “total amount” columns cell.

Additionally, a value in “split amount” cell should only appear if the value in the “SPLIT?” Columns cell is “yes” otherwise, it should be blank or 0.

Is this possible? I don’t know if it is but I think it’d be cool to have it be automatic. Imgur pic attached
https://imgur.com/a/hyZJxq8