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 16-3/4 liters per minute. The tank also has a drain that allows solution to leave the tank at a rate of
19-4/5 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?

(c) What does the change in volume after 15 seconds mean in the real world