A person walks up a stalled escalator in 90s. when standing on the same escalator, now moving, he is carried in 60s. The time he would take to walk up the moving escalator will be
t1=90s⇒90=dvm
speed of man =d90
t2=60⇒60=dvs
speed of escalator vs=d60
t=dvm+vs=dd/90+d/60=60×90150=36s