Which situation describes opposite quantities that when combined would equal 0?

Question

1. A plane ascends to 15,000 feet and then descends 10,000 feet. How many feet above the ground is the plane?
2. A plane ascends to 15,000 feet and then descends 15,000 feet. How many feet above the ground is the plane?
3. A plane ascends to 15,000 feet and then ascends 15,000 feet. How many feet above the ground is the plane?
4. A plane ascends to 10,000 feet and then ascends 15,000 feet. How many feet above the ground is the plane?

Answer 1

The situation that describes opposite quantities that when combined would equal 0 is:

2. A plane ascends to 15,000 feet and then descends 15,000 feet. How many feet above the ground is the plane?

In this case, the ascent of 15,000 feet and the descent of 15,000 feet are opposite quantities. When you add them together, they cancel each other out, resulting in a net change of 0 feet. Therefore, the plane is at ground level, or 0 feet above the ground.