Danka steps on the top stair of an escalator. When she is standing still, the escalator carries her to the bottom in t₁=2.0 min. If the escalator was not moving and Danka walked down it, it would take her t₂=2.5 min to get to the bottom. How long will it take her to get from the top to the bottom if she starts walking down the moving escalator in the middle of the path? Danka walks with constant velocity.