Two boys A and B start at the same time to ride from Delhi to Meerut, 60 km away. A travels 4 km an hour slower than B, B reaches Meerut and at once turns back meeting A, 12 km from Meerut. A’s rate was?
Note
Let A's speed = x km/hr.
Then, B's speed = (x + 4) km÷hr.
Clearly, the time taken by B to cover (60 + 12) i.e., 72 km
= time taken by A to cover (60 - 12) i.e. 48 km.
∴ {72 ÷ (x+4)} = (48 ÷ x)
⇒ 72x = 48x + 192
⇒ 24x = 192
⇒ x = 8.
Hence A's speed = 8 km/hr.