Abicycle rider travels 50.0 km in 2.5 hours. determine the cyclists average speed.

There are several information's already given in the question. Based on those information's the answer can be easily deduced.

Distance traveled by the bicycle rider = 50 km
Time taken to travel the distance = 2.5 hours
So
In 2.5 hours the bicycle rider travels = 50 km
Then
In 1 hour the bicycle rider travels = 50/2.5
                                                     = 20 km
Then the average speed of the cyclist is 20 km per hour.