Abus makes a stop at 2: 30, letting off 15 people and on 9 people. the bus makes another stop ten mins later to let off 4 more people. how does the number of people on the bus after the second stop compare to the number of people on the bus before the 2: 30 stop?

If you dont know. use x as your original value. Therefore. you would have:
 x - 15 + 9
after the second stop you would have:
 (x - 15 + 9) - 4

So your answer would either be...
     There was more people on the bus before 2:30 than there was after the second stop.
      There was more people on the bus after the second stop than there was before 2:30.