Spent a while trying to crack the simple logic to this. Got it eventually.
Happy new year all.
My solution - finally! Was determined to figure out the Optimization tool. It has been my arch nemesis for some time now. After this challenge.... still my arch nemesis. :) But I got there eventually!!
What a fun and Community-minded challenge... thanks to all who helped make a difference through both challenge completions AND personal contributions!! Just another example of how this Community is really making a difference in SO MANY WAYS. Love you guys. *tear* :)