Question 971001
slower cyclist is x kph
faster cyclist is x+4 kph 

in 1.5 hours, their distance is 39 km

39 km/1.5 hours is 26 kph

x+ (x+4) =26

2x +4=26
2x=22

x=11

x=4=15

They are traveling apart at 26 kph; in 1.5 hours they will be 39 km apart.

The slower is traveling at 11kph; the faster at 15 kph.