Need a second judgement

[CHelir2014]

I was working on this problem and checked my answer and the book said I was wrong.
The problem says: The peak of Mt.Kilimanjaro is 19,321 ft above sea level. Qattara Depression is the lowest point in Africa, 436 ft below sea level. What is the difference in elevation between the two?

Initially i just subtracted and got 18,885ft but the book says its 19,757ft.

 

[Deleted member 4993]

I was working on this problem and checked my answer and the book said I was wrong.
The problem says: The peak of Mt.Kilimanjaro is 19,321 ft above sea level. Qattara Depression is the lowest point in Africa, 436 ft below sea level. What is the difference in elevation between the two?

Initially i just subtracted and got 18,885ft but the book says its 19,757ft.

The peak of Mt.Kilimanjaro is 19,321 ft above sea level → elevation 19321 ft


Qattara Depression is the lowest point in Africa, 436 ft below sea level → elevation (-436)ft

difference in elevation = 19321 - (-436) = 19757 ft.

 

[JeffM]

I was working on this problem and checked my answer and the book said I was wrong.
The problem says: The peak of Mt.Kilimanjaro is 19,321 ft above sea level. Qattara Depression is the lowest point in Africa, 436 ft below sea level. What is the difference in elevation between the two?

Initially i just subtracted and got 18,885ft but the book says its 19,757ft.

You were right to subtract, but forgot how to subtract a negative number.

19,321 - (-436) = 19,321 + 436 = 19,757.

Why is this? Well if you were at the bottom of the basin you would have to climb upwards 436 feet just to get to sea level and then you would need to climb another 19,321 feet upwards to get to the top of the mountain so 436 + 19,321 = 19,757 feet upwards.