Mr. Parks begins to fill a large container with water for the dunk tank at the school fair before asking Brian to finish the job. The container has 25 gallons of water in it before Brian uses a hose to finish filling it up. The container fills at a rate of 10 gallons per minute. Suppose that y is the amount of water in the tank after x minutes. Which equation could be graphed to help Brian find out how much water is in the tank at any time?