Lizzy: 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?.
Me: Hmmm, let me think. I think this is the detailed solution:
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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. Final answer: 30.
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