A large tank contains 100 gallons of brine in which 10 lbs. of salt is dissolved. Brine containing 0.2 lbs. of salt to the gallon runs into the tank at the rate of 6 gal/min. The mixture, kept uniform...

A large tank contains 100 gallons of brine in which 10 lbs. of salt is dissolved. Brine containing 0.2 lbs. of salt to the gallon runs into the tank at the rate of 6 gal/min. The mixture, kept uniform by stirring, runs out of the tank at the rate of 4 gal/min. Find the amount of salt in the solution in the tank at the end of t min.