The speed of a boat in still water is 2km/hr. If its speed upstream be 1km/hr then speed of the stream is________?

A. 1.5km/hr
B. 3km/hr
C. 1km/hr
D. none
Explanation:
Let the speed of stream be x km/hr
Speed upstream = (2-x) km/hr = 2-x = 1 => x = 1 km/hr