Question

A car enters an interstate highway 15 mi north of a city. The car travels north at an average speed of 62.5 mph. Which equation models the car’s distance d from the city after traveling for h hours?

Answer 1

D(x)=62.5x+15  x is how far he goes when he travels 62.5 miles per hour.  Since he is already 15 miles north of the city we add that in as our "starting" distance.  On a graph, this would be the y-intercept and the speed would serve as the slope.  This is given as a linear relationship.