Danni races cars at her local racetrack. She drove her red car 400 meters in 5 seconds. If she drives the same car at the same rate, how fast will she be able to complete a race that is 600 meters?
Danni drove her red car at a speed of 400 meters/5 seconds = <<400/5=80>>80 meters/second.
If she drives the same car at the same rate, she will be able to complete a race of 600 meters in 600 meters / 80 meters/second = <<600/80=7.5>>7.5 seconds. Answer: \boxed{7.5}.