A large tank contains 350350 liters of a salt solution which has a concentration of 0.650.65 kilograms per liter. A salt solution which has a concentration of 0.80.8 kilograms per liter is added to the solution at a rate of 6060 liters per minute. At the same time, the solution drains from the tank at 6060 liters per minute. Find the amount SS of the salt in the solution as a function of tt: