Copper in 4 kg = 4/5 kg          and      Zinc in 4 kg = 4 x (4/5) kg   Copper in 5 kg = 5/6 kg          and      Zinc in 5 kg = 5 x (5/6) kg   Therefore, Copper in mixture =  4 5 + 5 6 = 49 30  kg   and  Zinc in the mixture = 16 5 + 25 6 = 221 30 kg   Therefore the required ratio = 49 : 221