Determine the initial value and the rate of change in the following description. A 2,000-gallon tank is half full with 1,000 gallons of water. Water is being pumped into the tank at a rate of 15 gallons per minute.
The initial value is b=___, and the rate of change is m= ____.
Initial value: 1,000 gallons (the amount of water in the tank initially)
Rate of change: 15 gallons per minute (the rate at which water is being pumped into the tank)