This is on the the application of differential equations.

A 200-gallon tank initially holds 50 gallons of salt solution containing 20 lbs dissolved salt.

A pipe fills the tank with 2 lbs of salt per gallon at a rate of 5 gpm. The mixture is stirred uniformly and 3 gpm of brine runs out of the tank.

a.) Draw the schematic diagram of the system showing the values given in the problem.

b.) Determine the amount of salt in the tank at the end of 85 minutes.