You have to use absolute value to change -922 into positive 922, and then add it to 11,542. That will give you the height of the surface above sea level. Therefore, your answer is 12,464 feet above sea level.
It is given that, the deepest point of lake Titicaca in south america is -922 feet relative to its surface. The deepest point is 11,542 feet above sea level. We need to find the elevation of the surface of the lake. Let it is equal to x.
x = height relative to its surface + height above sea level.
x = 922 feet + 11542 feet
x = 12464 feet
So, the elevation of the surface of the lake is 12464 feet. Hence, this is the required solution.
