Answer to Question #295341 in Engineering for Fernando

Question

A large tank initially contains 220 gal of brine where there is dissolved 35lb of salt. Starting

at time t = 0, a brine containing 3lb of dissolved salt per gallon flows into the tank at the rate of

6gal/min is kept uniform by stirring and the well-stirred mixture simultaneously flows out of the

tank at a slower rate of 3gal/min. How much salt is in the tank at the end of 20 min?