a Boat goes 12 kilometre in one hour how long will it take to go 90 km​

1hour = 60 minutes

12 kilometres - 60 minutes -> 1 kilometre = 60/12 = 5 minutes

90 kilometres: 5minutes*90 = 450 minutes = 450/60 hours = 7 hours 30 minutes or 7,5 hours.

7,5 hours.