A miner is drilling at a constant rate when her supervisor requests a status update. She looks at her drill’s depth gauge which says the elevation is 13 feet below ground level. 3 hours later, the drill’s elevation is 21 feet below ground level. A) At what rate is the drill’s elevation changing? Use a signed number, and include the unit of measurement in your answer.

B) How many more hours until she reaches her goal depth of 30 feet? Explain or show your reasoning.

C) How many hours before her team requested an update was the drill at the surface of the ground? Explain or show your reasoning.