Erica and Amy started biking in the opposite directions at the same time from the same place. Erica biked at a speed of 6 meters per second and Amy biked at a speed of 4 meters per second. How soon were they exactly 1km apart?
Since they are moving in opposite directions, this is the same as Amy staying still and Erica biking at 10 meters per second away from her.To travel 1km = 1000m at 10 meters per second, you need 1000/10 = 100
