Two men start together to walk a certain distance, one at 4 kmph and another at 3 kmph.The former arrives half an hour before the latter. Find the distance.
Pick.
A) 6 km
B) 7 km
C) 8 km
D) 9 km
E) none of these

Rationale: let the distance be x km . then , x / 3 - x / 4 = 1 / 2 ( 4 x - 3 x ) / 12 = 1 / 2 x = 6 km answer : a
Answer: A