A salt solution flows at a constant rate of 4 L/min into a large tank that initially contains 100L if pure water. The solution inside the tank is kept well stirred and flows out of the tank at a rate of 3 L/min.

A salt solution flows at a constant rate of 4 L/min into a large tank that initially contains 100L if pure water. The solution inside the tank is kept well stirred and flows out of the tank at a rate of 3 L/min. (a) If the concentration of the solution flowing into the tank is 0.2 kg/L, find a formula for x(t), the amount of salt (in kg) in tank at time t minutes after the solution begins to flow into the tank. (b) When will the concentration in the tank reach 0.01kg/L