11. A fish tank initially contains 800 grams of oxygen dissolved in 200 liters of water. Water containing 8 grams/liter of oxygen flows into the tank at a rate of 2 liters/min. The well-stirred mixture flows out of the tank at the same rate. Set up an initial value problem (that is, give both a differential equation and an initial condition) modeling this process that describes the amount of oxygen present in the tank at any time t> 0. а. b. Solve the initial value problem thus obtained.