Yeah, I saw that while searching for a solution.
I'll be honest, I didn't understand it completely.
I realised, shortly after posting my question that my game plan probably wont work anyway.
Thinking out loud....
If i add red-100,0,0
I get magenta.
Theres no other combinations left other than adding green to magenta, giving white.
All values will be 100 and the game technically over.
I wanted to keep combining coloures, creating many different ones!!
What can I do?