Average rate of change of a line is its slope.
To find slope we can use the formula:

Where,
- m is the slope
is the first point
is the second point
For our problem,
- Point 1 (
) is (0,100) - Point 2 (
) is (3,220)
Now, let's find slope.

So, the average rate of change of the function f(x) int he first three seconds is 40.
ANSWER: 40