Final answer:
The graph representing Adam's train ride at a constant speed of 60 miles per hour would be a straight line with a consistent slope on a distance-time graph.
Step-by-step explanation:
If Adam rode a train that traveled at a constant speed of 60 miles per hour, the graph representing the distance traveled by his train over time would be a straight line with a consistent slope. In such a graph, the y-axis would represent distance, and the x-axis would represent time. Because the train is moving at a constant speed, the line on the graph would not curve; it would rise at a steady rate reflecting the unchanging speed of the train. A graph such as this is known as a distance-time graph and depicts the relationship between the distance traveled and the time taken to travel that distance.