3. A large tank is partially filled with a solution. The tank has a faucet that allows solution to enter the tank at a rate of liters per minute. The tank also has a drain that allows solution to leave the tank at a rate of liters per minute. (a) What expression represents the change in volume of solution in the tank in 1 minute?
(b) What is the change in volume of the solution after 15 seconds? Show necessary work.
(c) What does the change in volume after 15 seconds mean in the real world? Answer in complete sentences.