standard_description: Graph proportional relationships, interpreting the unit rate as the slope of the graph. Compare two different proportional relationships represented in different ways. For example, compare a distance-time graph to a distance-time equation to determine which of two moving objects has greater speed.
problem_activity: Task
The graphs below show the distance two cars have traveled along the freeway over a period of several seconds. Car A is traveling 30 meters per second.
[IMG]
Which equation from those shown below is the best choice for describing the distance traveled by car B after $x$ seconds? Explain.
$y = 85x$
$y = 60x$
$y = 30x$
$y = 15x$


aligns: yes