 
 <translate> Speed in down stream = 10 +8 = 18
Time taken to cover 90 km down stream = 90/18 = 5 hrs.
The final answer: (B). <hau> Saurin saukar da ruwa = 10 + 8 = 18 Lokaci da aka ɗauka don rufe kilomita 90 a ƙasa = 90/18 = 5 hrs. Amsar ƙarshe: (B). 