Abrine solution of salt flows at a constant rate of 4l/min into a large tank that initially held 100l of pure water. the solution inside the tank is kept well-stirred and flows out of the tank at a rate of 3l/min. if the concentration of salt in the brine entering the tank is 0.2kg/l, determine the mass of the salt in the tank after t minutes. when will the concentration of salt in the tank reach 01.kg/l?