The change in elevation would be 14,130 3/4 feet.
Death Valley = - 212 3/4 feet (neg. because it’s below sea level)
Mt. Humphreys = 13,918 feet
The change in elevation is found by solving for the difference between the heights
13,918 - (-212 3/4)
13,918 + 212 3/4 = 14,130 3/4