So first, you get the absolute value to one side:

Next, set up two equations; One where the value inside the absolute value lines is positive, and another where it is negative, and solve both for the variable:

Your answers are
8 and -8, or +-8.
Step-by-step explanation:
Hope this helps you ☺️☺️☺️
Heinz,Pepsi,Coca-Cola,Kitkat
Answer:
+15
-721
0
+462
-1200
The positives are because it said 'above sea level', the negatives because it said 'below sea level' and zero because it said 'sea level'.