Math Problem (Level 2) : Walk on 40 steps escalator (DD6)

There is the up escalator in which there are 40 steps when it stops.
It was just in 16 steps when I walked on this escalator from the 1st floor to the 2nd floor.
What ratio is it between the speed of escalator and the speed of walk ? 





Answer
3 : 2

Solution
Because there is 40 steps of number of the steps, the escalator goes up 40 - 16 = 24 steps while 16 steps walk. 
The ratio of the speed is 24 : 16 = 3 : 2.