Atank initially contains 120 l of pure watera tank originally contains 100 gal of fresh water. then water containing 1 2 lb of salt per gallon is poured into the tank at a rate of 2 gal/min, and the mixture is allowed to leave at the same rate. after 10 min the process is stopped, and fresh water is poured into the tank at a rate of 2 gal/min, with the mixture again leaving at the same rate. find the amount of salt in the tank at the end of an additional 10 min. a mixture containing a concentration of γ g/l of salt enters the tank at a rate of 2 l/min, and the well-stirred mixture leaves the tank at the same rate. find an expression in terms of γ for the amount of salt in the tank at any time t. also find the limiting amount of salt in the tank as t → [infinity]