A tank contains 200 liters of fluid in which 30 grams of saltis dissolved. Brine containing 1 gram of salt per liter is thenpumped into the tank at a rate of 4L/min; the well mixed solutionis pumped out at the same rate. Find the number A(t) of gramsof salt in the tank at time t. Then solve the problem assuming thatpure water is pumped into the tank.