Answer:
The plane is 4,000 ft above the floor of the Grand Canyon
Explanation:
Here, we are interested in knowing how high is the plane from the floor of the Grand Canyon.
Mathematically, what we are to do here is to add distances.
The height of the plane is 2500 ft, while the floor of the Canyon at that point we are considering is 1500 ft deep into the ground.
Thus, the height of the plane above the Canyon floor at this point will be 2500 ft + 1500 ft = 4000 ft
So the plane is 4,000 ft above the floor of the Grand Canyon