Answer
The elevation difference is $19,757$ feet
Work Step by Step
The peak of Mount Kilimanjaro=$19,321$ feet
The Qattara Depression=$-436$ feet (negative because it is below sea level)
$ 19,321-(-436)\qquad$...change the subtraction to addition
$=19,321+436\qquad$...replace $-436$ with its opposite.
$=19,757$ feet
