6.75 per hour
121.50/18 = 6.75
Average rate of change of the function: 
Step-by-step explanation:
The average rate of change of a function f(x) can be calculated as:

where:
are the x-values of the interval taken into account to evaluate the rate of change of the function
are the values of the function at those points
In this problem, we have:

The function is
, so

So, the average rate of change in this interval is:

Learn more about rates of change:
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Step-by-step explanation:
76.72135955 is the answer I think So if the answer is correct then plz mark me as brainliest
David is correct because if the circle on the graph is filled in it means 17 or older but Lily’s represents older than 17