Kate likes to walk down moving escalators and she takes one step at a time. When she walks down at a rateof 2 steps per second, she reaches the bottom from the top after 18 steps. When she is exhausted, she will walk down at a rate of I step per second and she will reach the bottom from the top after 12 steps. Find the time
taken for her to reach the bottom from the top if she just stands on the escalator.