the relationship between time and distance remaining on a 3 mile walk for someone walking at steady rate of 2 miles per hour

Let d be the remaining distance.
Let t be the remaining time.

The standard distance equation is:
d = rt

We are given the rate as 2, so:
d = 2t

At the start of the walk, the remaining distance is 3 miles.
The remaining time is 1.5 hours.

At the end of the walk, the remaining distance is 0 miles.
The remaining time is 0 hours.

A graph of the distance and time would be a continuous, solid line. That's because the walker will be at every distance between 3 and 0 and every time between 1.5 and 0.


The graph of this would be a solid line