A tank initially contains 100 gallons of brine with 10 lb of salt dissolved in it. Brinecontaining 0.4 lb of salt per gallon ows from an outside source into the tank at a rateof 5 gal/min. The mixture is discharged out of the tank at the same rate of 5 gal/minAssume that solutions are well-stirred at all times.

Required:

Find the amount of salt in the tank at the end of 40 minutes.