Help me please (the problem is in the photo)

The highest point on earth is the peak of mount everest if you climb to the top you would be approximately 29,035 feet above sea level at remembering that amount is 5280 feet percentage of the height of the mountain would you have to climb to reach a point 2 miles above sea level

Whats the name of the vertical axis

Which of the following expressions is equal to 2x^2+8