Sanjay can row 60 kmph in still water and he finds that it takes him twice as much time to row up than as to row down the same distance in the river. The speed of current in kmph?

For boat and stream problems, if upstream time is twice downstream time, then speed upstream = 1/2 × speed downstream. Let boat speed = 60 kmph, current speed = c. Downstream: 60 + c. Upstream: 60 - c. Since time upstream = 2 × time downstream, (60 - c) = (1/2)(60 + c). Solving: 60 - c = 30 + c/2, giving 30 = 3c/2, so c = 20 kmph. Option B is correct.