It takes Mr. Been 90 seconds to walk up an escalator when it is not moving. It takes Mr. Been 60 seconds to go up, just standing when the same escalator is moving. How many seconds does it take Mr. Been to walk up the moving escalator?
I think it would take an average of both the numbers so first find the average of 60 and 90 by adding and dividing by two. You will get 75 seconds. That is the answer
