A mountain road is 5 miles long and gains elevation at a constant rate. After 2 miles, the elevation is 5500 feet above sea level. After 4 miles, the elevation is 6200 feet above sea level.[list=1][*]Find the elevation of the road at the point where the road begins.[/*][*]Describe where you would see the point in part (a) on a graph where yrepresents the elevation in feet and x represents the distance along the road in miles.[/*][/list]

Suppose that during its flight, the elevation e (in feet) of a certain airplane and its time t, in minutes since takeoff, are related by a linear equation. Consider the graph of this equation, with time represented on the horizontal axis and elevation on the vertical axis. For each situation, decide if the slope is positive, zero, or negative.[list=1][*]The plane is cruising at an altitude of 37,000 feet above sea level.[/*][*]The plane is descending at rate of 1000 feet per minute.[/*][*]The plane is ascending at a rate of 2000 feet per minute.[/*][/list]