 <translate> Speed downstream = d/t = 90/(2 1/2) = 36 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (36 - 18)/2 = 9 kmph
Therefore, the answer is (A). <yor> Iyara ìsàlẹ̀ odò = d/t = 90/(2 1/2) = 36 kmph Iyara ti o wa ni oke = d/t = 45/(2 1/2) = 18 kmph Iyara ti odò = (36 - 18)/2 = 9 kmph Nítorí náà, ìdáhùn náà ni (A). 