A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is

Explanation

Downstream speed = speed in still water + stream speed. Therefore, speed in still water = 15 2.5 = 12.5 km/hr. Against the current, subtract the stream speed again: 12.5 2.5 = 10 km/hr. This gives 10 km/hr.