Final answer:
The elevation 112 meters below sea level is represented by the number -112 meters. Elevations above sea level are positive, and those below are negative.
Step-by-step explanation:
The question you are asking about is related to elevations above and below sea level. In your case, a city has an elevation of 3869 meters above sea level. To represent an elevation that is 112 meters below sea level, you would use a negative number. Therefore, the number that represents an elevation of 112 meters below sea level would be -112 meters.
Regarding the example provided concerning air density and altitude, as elevation increases, such as from 4,000 meters to 6,000 meters, the air density decreases. This is captured by the change in air density per meter of altitude change, calculated using the rise over the run. For every additional 1,000 meters, the air density drops by approximately 0.1 kilograms per cubic meter, indicating a slope of -0.207.