Ravi and Ajay start simultaneously from a place A towards B, 60 km apart. Ravi's speed is 4 km/hr less than that of Ajay, after reaching B, Ajay turns back and meet Ravi at a place 12 km away from B, Ravi's speed is :

Let the speed of Ravi = x km/hr
Then Ajay's speed will be = (x + 4) km/hr
Total distance, covered by Ajay :
= (60 + 12) km
= 72 km
Total distance, covered by Ravi :
= (60 - 12) km
= 48 km
According to the question,
They run at same time
$$\eqalign{ & \Rightarrow \frac{{72}}{{(x + 4)}} = \frac{{48}}{x} \cr & \Rightarrow 72x = 48x + 192 \cr & \Rightarrow 24x = 192 \cr & \Rightarrow x = 8{\text{ km/hr}} \cr} $$
Therefore, Ravi's speed = 8 km/hr