 
<translate> Speed na ala iyi = 10 + 8 = 18 Oge a ga-eji mee njem kilomita iri itoolu = 90/18 = awa ise. Azịza ya bụ: (B). <eng> Speed in down stream = 10 +8 = 18
Time taken to cover 90 km down stream = 90/18 = 5 hrs.
The final answer: (B). 