a person walks from one end to the other of a 100 - meter long moving walkway at a constant rate in 25 seconds , assisted by the walkway . when this person reaches the end , they reverse direction and continue walking with the same speed , but this time it takes 150 seconds because the person is traveling against the direction of the moving walkway . if the walkway were to stop moving , how many seconds would it take this person to walk from one end of the walkway to the other ?
"let v be the speed of the person and let x be the speed of the walkway . 25 ( v + x ) = 100 then 150 ( v + x ) = 600 150 ( v - x ) = 100 when we add the two equations : 300 v = 700 v = 7 / 3 time = 100 / ( 7 / 3 ) = ( 300 / 7 ) seconds which is about 43 seconds the answer is d ."
divide(100, divide(add(divide(100, 25), divide(100, 150)), const_2))