In five days, four black cows and three brown cows give as much milk, as five brown cows and three black cows would give in four days.
Which color cows are the best milk producers?
It seems that it takes 8 cows to produce in four days what 7 cows can produce in five days. If you were to add one brown cow to even the number of cows if seems you would not make the four day deadline. So you must substitute a black cow for another brown cow to make up the difference in milk production. Therefore the brown cows produce more milk.
well
