arithmetic - x can row at a speed of 18 kmph in still waterif it takes him thrice as long to row up as to row down the riverfind the rate of stream - skillgun

Let X’s rate upstream be x kmph.
then ,his rate downstream= 3x kmph.
So, 2x = 18
or x = 9.
Rate upstream=9 km/hr,rate downstream = 27 km/hr.
Hence,rate of stream = 1/2(27-9)km/hr = 9 km/hr.