There were 120 litres of pure milk in a vessel. Some quantity of milk was taken out and replaced with 23 litres of water. thus the resultant ratio of the quantity of milk to water is 4:1. Again 23 litres of the mixture was taken out and replaced with 28 litre of water. What is the ratio of the milk to water in the resultant mixture?

First replacement: After removing x litres and adding 23 L water, milk:water = 4:1 with total 120 L. So milk = 96 L, water = 24 L, meaning x = 24 L milk was removed. Second replacement: From 96 L milk + 24 L water, removing 23 L mixture removes (23×96/120) = 18.4 L milk and (23×24/120) = 4.6 L water. Remaining: 77.6 L milk + 19.4 L water. Adding 28 L water: milk = 77.6 L, water = 47.4 L. Ratio = 77.6:47.4 = 46:29.