If a boat rows 40 km/hr upstream and 60 km/hr downstream, then the speed of the boat in still water and the speed of stream respectively will be:

50 km/hr and 10 km/hr

The correct answer is Option (1) → 50 km/hr and 10 km/hr

$u - v = 40,\;\; u + v = 60$

$u = \frac{40 + 60}{2} = 50$

$v = \frac{60 - 40}{2} = 10$

The speeds are $50$ km/hr and $10$ km/hr respectively.