Mount McKinley in Alaska, the highest mountain in North America, is 20,320 feet above sea level. Dea

Mount McKinley in Alaska, the highest mountain in North America, is 20,320 feet above sea level. Death Valley, the lowest point, is 280 feet below sea level. What is the difference in height between Mount McKinley and Death Valley?

Regarding height with respect to sea level...

• Above sea level is written as positive height
• Below sea level is written as negative height

So we have:
+20,320 - -280
+20,320 + 280
20,600