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?	Options:
A) 80
B) 90
C) 100
D) 110
E) 120

Rationale: lets suppose that a walks down 1 step / min and escalator moves n steps / min it is given that a takes 50 steps to reach the bottom in the same time escalator would have covered 50 n steps so total steps on escalator is 50 + 50 n . again it is given that b takes 90 steps to reach the bottom and time taken by him for this is equal to time taken by a to cover 10 steps i . e 10 minutes . so in this 10 min escalator would have covered 10 n steps . so total steps on escalatro is 90 + 10 n again equating 50 + 50 n = 90 + 10 n we get n = 1 hence total no . of steps on escalator is 100 . answer : c
Answer: C