A car averages 50 mph for the first 4 hours of a trip and averages 80 mph for each additional hour. The average speed for the entire trip was 65 mph. How many hours long is the trip? Choose the correct option
A) 8	B) 7	C) 6	D) 5	E) 4

Rationale: let the time for which car averages 80 mph = t 65 * ( t + 4 ) = 50 * 4 + 80 t = > 15 t = 60 = > t = 4 total duration of the trip = 4 + 4 = 8 answer a
Answer: A