In this introductory course to compositing in Unreal Engine, you’ll learn the basics of creating an A over B composite. Follow along and learn different techniques to get the best results from the Composure plugin.
https://dev.epicgames.com/community/learning/courses/ePb/unreal-engine-real-time-compositing-basics
I repeated the course many times I didnot understand anything
your way to explain is completely different
first of all you are adding the functions from right to left and second you dont give an example about the the result of what you are explaining