 
<translate> Ọsọ n'okpuru mmiri = 50 + 20 = 70 kmph Speed elu iyi = 50 - 20 = 30 kmph N'ihi ya, azịza ya bụ (A). <eng> Speed downstream = 50 + 20 = 70 kmph
Speed upstream = 50 - 20 = 30 kmph
Therefore, the answer is (A). 