Ojos del Salado is the highest mountain in Chile, with a peak at about 6900 meters above sea level. The Atacama Trench, just off the coast of Peru and Chile, is about 8100 meters below sea level (at its lowest point). a. What is the difference in elevations between Mount Ojos del Salado and the Atacama Trench?

b. Is the elevation halfway between the peak of Mount Ojos del Salado and the Atacama Trench above sea level or below sea level?

Explain without calculating the exact value. c. What elevation is halfway between the peak of Mount Ojos del Salado and the Atacama Trench?