Answer:
Since, speed of a car = distance traveled/time taken
From the graph attached,
A point (1, 60) lies on the line shown in graph.
At this point speed of the car =
= 60 miles per hour
But Billy says the speed of the car is 1/60 miles per hour.
So the error in the Billy's answer is that he has used the wrong formula to calculate the speed.
(As per Billy, speed = )
Explanation: