Two sisters go up 40-step escalators. The older sister rides the up escalator, but can only take 10 steps up during the ride since it is quite crowded. The younger sister runs up the empty down escalator, arriving at the top at the same time as her sister. How many steps does the younger sister take?
+36916 Sister going UP only let escaloator cover 30 steps in the 15 seconds
sister going down has to cover those 30 plus the 40 steps of the original length = 70 steps
