1. A large tank has 9 gallons of water in it. Water begins flowing into the tank. (5 points) a. Define a variable that represents how much water is added to the tank. Use precision when defining your variable. (1 point) b. Use your variable to write an expression that represents the number of gallons in the tank. (2 points) c. Explain how your expression connects to the given scenario. (What do your numbers represent? Why did you use an operation like addition, subtraction, multiplication, or division in your expression?) (2 points)