A Drug Is Carried into an Organ of Volume

Essay

A drug is carried into an organ of volume cm³ by a liquid that enters the organ at the rate of a cm³/sec and leaves it at the rate of b cm³/sec. The concentration of the drug in the liquid entering the organ is c g/cm³. If the concentration of the drug in the organ at time is increasing at the rate of
​ ​g/cm³/sec, and the concentration of the drug in the organ initially is g/cm³, show that the concentration of the drug in the organ at time is given by
​