Brian takes the underground train to work and uses an escalator at the railway station. If Brian runs up 6 steps of the escalator, then it takes him 39.0 seconds to reach the top of the escalator. If he runs up 13 steps of the escalator, then it takes him only 28.5 seconds to reach the top. How many seconds would it take Brian to reach the top if he did not run up any steps of the escalator at all?