Answer:
15 mph
Explanation:
The cyclists will cover distance at a rate proportional to their speed. So, the distance ratio is ...
faster cyclist distance : slower cyclist distance = 3 : 1
Then the faster cyclist covers 3 : (3+1) = 3/4 of the total distance, or (3/4)(40 mi) = 30 mi.
That distance took 2 hours for the faster cyclist, so the speed was ...
speed = distance/time = 30 mi/(2 h) = 15 mi/h