1. Consider a large tank holding 100 L of pure water into which a brine solution of salt begins to flow at a constant rate of 6 L/min. The solution inside the tank is kept well stirred and is flowing out at a rate of 6 L/min. The concentration of salt in the brine entering the tank is 0.1kg/L. See the figure below. a. Carefully set up the differential equation for the amount of salt in the tank. Use i for time, x for the amount of salt, and s for the amount of solution. b. Do a seven step phase line analysis for the differential equation of part (a). c. Using the TI RK32 method, find to two decimal place accuracy the concentration (not the amount) of salt in the tank in 30 minutes. Justify the accuracy.