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 1 km apart?

The time at which they were exactly 1 km apart is; 100 seconds

We are told that Erica biked at a speed of 6 m/s while amy biked at a speed of 4 m/s.

Thus;

6m/s = 0.006 km/s

4 m/s = 0.004 km/s

We know that speed * time = distance.

Thus, for them to be 1 km apart;

0.006t + 0.004t = 1

0.01t = 1

t = 1/0.01

t = 100 s

Read more about distance at; link

The answer is = x + 1