2. ( 3 marks) Pure water flows into a tank at a rate of 10L/min. The contents of the tank are preserved and mixed well. The contents flow out at a rate of 10L/min. Initially, the tank contained 10kg of salt in 100 liters of water. How much salt will there be in the tank after 30 minutes? 3. (2 marks) Pure water flows into a tank at a rate of 8L/min. The contents of the tank are preserved and mixed well, and the contents flow out at a rate of 10L/min. Initially, the tank contained 10kg of salt in 100 liters of water. How much salt will there be in the tank after 30 minutes