3. A well stirred tank contains 600 kg of solution with a concentration of 7% sucrose. A constant flow rate of 800 kg/h of sucrose solution containing 12% sucrose is suddenly introduced into the tank and a constant withdrawal rate of 500 kg/h is also started. These two flows remain constant thereafter. Derive an equation relating the outlet withdrawal concentration as a function of time. Also, calculate the concentration of sucrose solution in the tank after 3 hours