Maria bicycles 4km/h faster than Javier. In the same time that it takes Javier to bike 60km, Maria bikes 72km. How fast does each bicyclist travel?
m=j+4
60/j = 72/m
60/j = 72/(j+4)
60(j+4) = 72j
60j + 240 = 72j
240 = 12j
20 = j
24 = m
They both bike for 3 hours to cover the indicated distances.