###Human: A building has 10 floors. It takes 15 seconds to go up the stairs to the even-numbered floors and 9 seconds to go up to the odd-numbered floors.  This includes getting to the first floor. How many minutes does it take to get to the 10th floor?, ### Assistant: So for all even-numbered floors (2, 4, 6, 8, 10), it takes 5*15= 75 seconds
And for all odd-numbered floors (1, 3, 5, 7, 9) it takes 5*9= 45 seconds
To climb all the floors, it takes 75+45= 120 seconds
So it takes 120/60=2 minutes to get to the 10th floor 
 So the answer is :  2