The graph below plots a function f(x):

if x represents time, the average rate of change of the function f(x) in the first three seconds is

If x represents time, the average rate of change of the function f(x) in the first three seconds is  40.

We know that the average rate of change which is also know as a slope of a function from x=a to x=b is calculated by the formula:

Here we are asked to find the average rate of change between x=0 to x=3 ( i.e. in the first three seconds)

It is calculated as follows:

john earns $14.00 for two hours of work.

its a straight line parallel to the time axis