Casey was at the surface of a swimming pool and recorded the following two measurements, in feet, on a number line:

−8, which represents the depth of water in the swimming pool
+7, which represents the height of the slide at the pool

Part A: What does 0 represent in this situation? (3 points)

Part B: Describe the height of the slide in relation to 0 in the situation. (3 points)

Part C: Casey held a pole in the swimming pool. The bottom of the pole was at a depth of 2 feet. How should Casey mark the level of the bottom of the pole on the number line? Explain how you determined this. (4 points)