a bicyclist travels for 2h at an average speed of 12km/h. how far does the bicyclist travel ? at this speed how long will it take the bicyclist to at 54km?
to go for 2 hrs at 12 km/h will take you 24 km
so use a ratio:
2/t = 24/54
24t = 108
t = 108/24 hrs or 4.5 hrs