4. Mixing Concentrations (Differential Equations) Consider a one-litre tank filled with a saline solution with an initial concentration of 5 g/L. Saline solution with a concentration of 25 g/L flows into the tank at a rate of 8 L/s, while thoroughly mixed solution flows out of the tank at 8 L/s (see figure below): Stirring device Inflow rate R Inflow concentration C; Volume V Outflow rate R a) Obtain the mass of the salt in the tank at any time t≥ 0 b) Obtain the concentration of the solution in the tank at any time t≥ 0