A tank initially contains 60 gal of pure water. Brine containing 4 lb of salt per gallon enters the tank at 2 gal/min, and the (perfectly mixed) solution leaves the tank at 3 gal/min. Thus, the tank is empty after exactly 1 h. (a) Find the amount of salt in the tank after t minutes. (b) What is the maximum amount of salt ever in the tank? (a) The amount of salt x in the tank after t minutes is x = (b) The maximum amount of salt in the tank was about (Type an integer or decimal rounded to two decimal places as needed.)