15.
At 9:00 on Saturday morning, two bicyclists heading in opposite directions pass each other on a bicycle path.The bicyclist heading north is riding 4 km/hour faster than the bicyclist heading south. At 10:15, they are 40 km apart. Find the two bicyclists’ rates.

northbound bicyclist = 19 km/h; southbound bicyclist = 15 km/h

northbound bicyclist = 18 km/h; southbound bicyclist = 14 km/h

northbound bicyclist = 18 km/h; southbound bicyclist = 13 km/h

northbound bicyclist = 16 km/h; southbound bicyclist = 10 km/h