a mountain, 100 feet above sea level, is near a valley 700 feet below sea level. How many feet higher is the mountain than the valley?

800 feet

Right.

To determine the height difference between the mountain and the valley, we need to find the total difference in elevation.

The mountain is 100 feet above sea level, and the valley is 700 feet below sea level.

To find the total difference, we add the elevation of the mountain to the elevation of the valley:

100 feet above sea level + 700 feet below sea level = 800 feet

Therefore, the mountain is 800 feet higher than the valley.