How Many Steps Visible on an Inactive Escalator?

[viren_t2005]

An escalator is descending at constant speed . A walks down and takes 50 steps to reach the bottom. B runs down and takes 90 steps in the same time as A takes 10 steps. How many steps are visible when the escalator is not operating?

 

[HallsofIvy]

You have posted 7 problems in a row without showing any attempt to do them yourself! The only way to learn mathematics is to do mathematics- yourself!