A man covered a certain distance at some speed. If he had moved 3 kmph faster, he would have taken 40 minutes less. If he had moved 2 kmph slower, he would have taken 40 minutes more. What is the distance in km?	Choose the correct choice
A) 36
B) 38
C) 40
D) 42
E) 45

Rationale: explanation : speed = 2 v 1 v 2 / v 1 − v 2 = 2 × 3 × 23 − 2 = 12 km / h = hr distance = vt 1 ( 1 + v / v 1 ) = 12 × 40 / 60 ( 1 + 12 / 3 ) = 40 km answer is c
Answer: C