A tank originally contains 350 gal of fresh water. Then water containing 0.2 lb of salt per gallon is poured into the tank at a rate of 8 gal/min, and the mixture is allowed to leave at the same rate. After 4 min the process is stopped, and fresh water is poured into the tank at a rate of 8 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 4 min.
There are lbs of salt in the tank.