###Human: Austin and Jake start descending from the 9th floor of a building at the same time. Austin uses the elevator and Jake uses the stairs, descending 3 steps every second. The stairs have 30 steps across each floor. If the elevator will take a minute to get to ground level, how many seconds later will Jake get to the ground floor?, ### Assistant: Jake has to descend 30 steps on 9 floors for a total of 9*30 = 270 steps
He descends 3 steps every second so he will descend 270 steps in 270/3 = 90 seconds.
Austin will get down after only a minute (60 seconds) so Jake will get down 90-60 = 30 seconds later. 
 So the answer is :  30