A plane takes off and climbs steadily for 15 minutes until it reaches 30,000 feet. It travels at that altitude for 2 hours until it begins to takes 15 minutes at a constant rate. The graph provided below shows the plane's flight.
Height (feet)
000 OE
Time (hours)
a. Identify whether the graph is discrete or continuous
b. Determine the domain and range.
c. Identify key features of the graph (intervals of increase, decrease, and constants) and interpret them in the context of the situation,