The speed of a car is 100 km in the first hour and 60 km in the second hour. What is the average speed of the car?	Choose the correct choice.
A) 12 B) 75 C) 80 D) 54 E) 15

Rationale: "s = ( 100 + 60 ) / 2 = 80 kmph answer : c"
Answer: C