Alligation or Mixture - General Questions

In what ratio must rice at Rs. 31 per kg be mixed with rice at Rs. 57 per kg so that the mixture costs Rs. 38 per kg?

A container has 120 litres of milk. 10 litres are taken out and replaced with water. This is done 3 times in all. How much milk is left in the container?

How many kg of tea at Rs. 56 per kg must be mixed with 22 kg of tea at Rs. 17 per kg so that the mixture is worth Rs. 55 per kg?

A container has 60 litres of milk. 4 litres are taken out and replaced with water. This is done 3 times in all. How much milk is left in the container?

A mixture of 24 litres contains milk and water in the ratio 5 : 1. If 20 litres of water is added, what is the new ratio of milk to water?