speed of a boat in standing water is 9 kmph and the speed of the stream is 6 kmph . a man rows to place at a distance of 170 km and comes back to the starting point . the total time taken by him is :
"sol . speed upstream = 3 kmph ; speed downstream = 15 kmph . ∴ total time taken = [ 105 / 7.5 + 105 / 10.5 ] hours = 68 hours . answer b"
add(divide(170, add(9, 6)), divide(170, subtract(9, 6)))