The yield of butter from cream is 2/9 of the mass of cream, and the yield of cream from milk

The yield of butter from cream is 2/9 of the mass of cream, and the yield of cream from milk is 4/25 of the mass of milk. How much milk does it take to make 24 kg of butter?

You need to get 24 kg of butter, and the yield of butter from cream is 2/9 of the mass of cream, which means that to get 24 kg of butter you will need:
1) 24: (2/9) = 24 * (9/2) = (24 * 9) / 2 = 216/2 = 108 (kg) cream will be required to make

You need to get 108 kg of cream, and the yield of cream from milk is 4/25 of the mass of milk, which means that to get 108 kg of cream you will need:
2) 108: (4/25) = 108 * (25/4) = (108 * 25) / 4 = 2700/4 = 675 (kg) milk needed to make

Answer: You need 675 kg of milk.