posted by winterWX .
A person walks up a stalled 20 m long escalator in 79 s. When standing on the same escalator, now moving, the person is carried up in 60 s. How much time would it take that person to walk up the moving escalator?
ratewalking= 20/79 ratemoving=20/60
time= distance/added rates
so add the rates, and divide into distance.