A 10-litre solution of milk and water contains 8 litres of milk. 2 litres of the solution is replaced by pure milk and mixed. The process is repeated two more times. How much milk (in litres) is present in the mixture so obtained?

A vessel has 20 litres of milk. From this vessel, 5 litres of milk is taken out and replaced by water. The process is repeated once more. Find the quantity of milk (in litres) remaining in the vessel.

A shopkeeper mixes 40 kg of rice costing ₹30/kg with 60 kg of rice costing ₹50/kg. What is the average price (in ₹/kg) of the mixture?