A car averages 70 mph for the first 4 hours of a trip and averages 60 mph for each additional hour. The average speed for the entire trip was 65 mph. How many hours long is the trip?  Select the correct option.
A) 8
B) 9
C) 10
D) 11
E) 12

Rationale: "let the time for which car averages 60 mph = t 65 * ( t + 4 ) = 70 * 4 + 60 t = > 5 t = 20 = > t = 4 total duration of the trip = 4 + 4 = 8 answer a"
Answer: A