Posted by Sandi on .
Maria bicycles 6km/h faster than Praedup. In the same time it takes Praedup to bicycle 54km, Maria can bicycle 72km. How fast does each bicyclist travel?

Algebra 
Dr. Jane,
Distance = Rate x Time
Maria's rate is t km/hr faster than Praedup.
Maria: (r+6)t = 72
praedup rt = 45
Solve for t in each case:
t = 72/(r+6)
t = 45/r
Since the times are the same the two fractions equal each other. Solve for r.