A tank contains 100 liters of liquid, in which 35 grams of chemical x has been dissolved. If fluid having 4 grams of chemical x per liter enters the tank at the rate of 3 liters per minute and the well-mixed solution exits the tank at 5 liters per minute, A) Find the formula for the amount A(t) of chemical x in the tank at time t. B) Also, during this fill and drain process, what is the maximum amount of chemical X in the tank? A simple, step-by-step guide for converting these kinds of word problems to differential equations would be a nice addition to the steps used to set it up and solve it.