Story problem: Mount Saint Helens, a volcano, erupted on May 18, 1980. Before the eruption, Mount St. Helens was 2,950 meters high. After the eruption, it was 2,550 meters high. Question 1: what is the difference in height of Mount St. Helens before and after the eruption, expressed in meters? Question 2: Before the eruption, how many kilometers high was Mount St. Helens?