One dozen eggs is 48 eggs. Altogether that costs 40 dollars. If six of the eggs were broken then the money wasted would be 5 dollars.
The reason that it is 5 dollars is becuase it takes 10 to buy 12 eggs, and half of that is 6. So divide both 12 and 10 (separately) and you get 5 dollars for 6 eggs.
To get the percent you must divide 5 by 40.
The answer comes out to about 12.5% or 0.125.
So in the end, 12.5% of the money was wasted due to the broken eggs.
Hope this helped!