Suppose that during its flight, the elevation (in feet) of a certain airplane and its time 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.

1. The plane is cruising at an altitude of 37,000 feet above sea level.
2. The plane is descending at a rate of 1,000 feet per minute.
3. The plane is ascending at a rate of 2,000 feet per minute.

A group of hikers park their car at a trail head and walk into the forest to a campsite. The next morning, they head out on a hike from their campsite walking at a steady rate. The graph shows their distance in miles, , from the car after hours of hiking.

1. How far is the campsite from their car? Explain how you know.
2. Write an equation that describes the relationship between and .
3. After how many hours of hiking will they be 16 miles from their car? Explain or show your reasoning.

Elena’s aunt pays her $1 for each call she makes to let people know about her aunt’s new business

Select all the statements about the situation that are true.

Each square on a grid represents 1 unit on each side. Match the graphs with the slopes of the lines.

• 4