I am, either blind, or stupid, but I do not understand, how we receive 30% and 20% in the line "Large"
we have total RED as 40% which will be RED/SMALL and RED/LARGE. Now we know that RED/SMALL is 10% so RED/LARGE will be 40-10 = 30%.
now total LARGE is 50% out of which RED/LARGE is 30% so GREEN/LARGE will be 50 -30 = 20%
hope this helps.