A man can row at 4 kmph in still water. If the velocity of the current is 2 kmph and it takes him 12 hours to row to a place and comes back, how far is the place?

Question: A man can row at 4 kmph in still water. If the velocity of the current is 2 kmph and it takes him 12 hours to row to a place and comes back, how far is the place?

Solution:
Downstream speed = (4 + 2) = 6 kmph
Upstream speed = (4 - 2) = 2 kmph

Let, the required distance be = a km

ATQ,
(a/6) + (a/2) = 12
⇒ (a + 3a)/6 = 12
⇒ 4a = 72
⇒ a = 18