The average speed of a car decreased by 3 miles per hour every successive 8-minutes interval. If the car traveled 3.6 miles in the fifth 8-minute interval, what was the average speed of the car, in miles per hour, in the first 8 minute interval?
Choose one:
A) 31  B) 35  C) 39  D) 43  E) 47
(3.6 miles / 8 minutes)*60 minutes/hour = 27 mph   Let x be the original speed.   x - 4(3) = 27   x = 39 mph   The answer is 39.
<result>C</result>
The average speed of a car decreased by 3 miles per hour every successive 8-minutes interval. If the car traveled 3.6 miles in the fifth 8-minute interval, what was the average speed of the car, in miles per hour, in the first 8 minute interval?