A car is 10 miles from Richmond at 1:00 P.M
and 100 miles from Richmond at 3:00 P.M.
The average rate of change of this distance is the change in distance (100 miles - 10 miles) = 90 miles divided by the change in time (3:00 - 1:00) = 2 hours.
Average rate of change = (90 mi)/(2hr) = 45 mi/hr.
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