Tanks A and B contain mixtures of water and pollutant. Tank A has a 100 gallon capacity and is full. Tank B is also full and has a 200 gallon capacity. Initially, tank A contains 40 pounds of pollutant and tank B contains pure water (no pollutant). At , pure water begins pouring into tank A at a rate of 10 gallons per minute. The mixture flows from tank A into tank B at a rate of 10 gallons per minute, and drains out of tank B at 10 gallons per minute. If and represent the number of pounds of pollutant in tank A and tank B, respectively, then we have where and . Estimate the maximum amount of pollutant in tank B and the time that it occurs. Multiple answers for partial points.