A trained covered x km at 30 kmph and another 2x km at 20 kmph. Find the average speed of the train in covering the entire 3x km.	Choose the correct choice from the following answers:
A) 22.5
B) 99
C) 24
D) 66
E) 887

Rationale: "total time taken = x / 30 + 2 x / 20 hours = 2 x / 15 hours average speed = 3 x / ( 2 x / 15 ) = 22.5 kmph answer : a"
Answer: A