Two men start together to walk a certain distance, one at 4 km/hr and another at 3 km/hr. The former arrives half an hour before the latter. Find the distance :

Solution (By Examveda Team)

If the required distance be x km, then
$$\eqalign{ & \frac{x}{3} - \frac{x}{4} = \frac{1}{2} \cr & \Rightarrow \frac{{4x - 3x}}{{12}} = \frac{1}{2} \cr & \Rightarrow \frac{x}{{12}} = \frac{1}{2} \cr & \Rightarrow x = 6\,\,{\text{km}} \cr} $$