Posted by Rebecca on Wednesday, January 4, 2012 at 3:26pm.
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 5 km/hour faster than the bicyclist heading south. At 10:30, they are 40.5 km apart. find both of their rates.

7th Grade Math  Steve, Wednesday, January 4, 2012 at 4:22pm
Since they are heading north and south, let the southern speed be s, so the northern speed is s+5
After 1.5 hours, the distance is 40.5km
distance is speed * time
40.5 = (s + s+5) * 1.5
27 = 2s+5
22 = 2s
s = 11
so, the cyclist going south moves at 11km/hr, north at 16 km/hr
they are moving apart at 27km/hr, so at 1.5 hours they are 40.5 km apart.