Relate values of two columns in the same table (Power Query)

First, my apologies because this must be easy and already answered, but I can't figure it out, nor find a post with a solution.

I think two images will show what I am trying to do much better than what I could explain, so here they are:

InputWanted output   

I need to do it with Power Query and not DAX because the actual tables are a little bit trickier...

I appreciate your help :)