Lets use the formula y=mx+b
Our Y is Distance, and X is Hours
If the car is traveling at the constant rate of 55 mph that will be our slope or our M
Since the car can not start in a position ahead or behind where it begins our B will be 0
This leaves us with y=55x, it can also be written as d=55h
The graph will be a linear line increasing with a slope of 55