A car averages 30 miles per hour for the first 5 hours of a trip and averages 42 miles per hour for the rest of the trip. If the average speed for the entire trip is 34 miles per hour, how many hours long is the trip? Choose the correct choice:
A) 6.5	B) 7.5	C) 8.5	D) 9.5	E) 10.5
Let T be the total time of the trip.   30*5 + 42(T-5) = 34T   8T = 210-150   T = 7.5   The answer is 7.5.
<result>B</result>
A car averages 30 miles per hour for the first 5 hours of a trip and averages 42 miles per hour for the rest of the trip. If the average speed for the entire trip is 34 miles per hour, how many hours long is the trip?