Both time and distance start at zero. The distance traveled goes from 0 to 300
The time goes from 300/55 = 5.4545
The direct constant of proportionality = 55
The equation is set up so that d = r * t
So the domain is t and it goes from 0 ≤ t ≤ 5.4545
The range is the distance. It goes from 0 ≤ d ≤ 300
See the graph below.