A tank contains $60$ kg of salt and $2000$ L of water. A solution of a concentration $0.015$ kg of salt per liter enters a tank at the rate $6$ L/min. The solution is mixed and drains from the tank at the same rate.


a.) What is the concentration of our solution in the tank initially?

concentration = (kg/L)


b.) Find the amount of salt in the tank after $4.5$ hours.

amount = (kg)


c.) Find the concentration of salt in the solution in the tank as time approaches infinity.

concentration = (kg/L)