Answer:
Hₐ (airplane) = H₀ +25,000
Hₐ (submarine) = H₀ -600
Difference in elevation = 25,600 ft
Explanation:
Let the reference point be Sea level
Let the Height at sea level = H₀
Let the height above or below sea level = H₁
Total Height with respect to sea level = Hₐ
Hₐ =H₀ ± H₁--------------------------------------------------------------------- (1)
Where:
(+) is used for height above sea level
(-) is used for height below sea level
For the airplane :
Hₐ (airplane) =H₀ + H₁
= H₀ + 25,000----------------------------------------------------- (2)
For the Submarine;
Hₐ (submarine) =H₀ - H₁
=H₀ -600
Summarily:
Hₐ (airplane) = H₀ +25,000
Hₐ (submarine) = H₀ -600
H₀ is common in both expressions for the respective heights. The difference in elevation is given by :
Hₐ (airplane) -Hₐ (submarine) = (H₀ +25,000 ) -(H₀ -600)
= 25,600 ft