> John is in a train moving west at ten miles per hour. Jill is in a train moving north at twenty miles per hour. How fast are John and Jill moving apart from e

> John is in a train moving west at ten miles per hour. Jill is in a train moving north at twenty miles per hour. How fast are John and Jill moving apart from each other? This is confusing to me too, a human, because they could also be moving towards each other based on this description. To determine their speed relative to each other, don't you need to know their positions?