Igot the answer but i need to know how did she get that answer

If you round your numbers that is how you find your answer.  Rounding rules:  5 or more round up to the next number.  4 or less stays the same.  This problem requires you to round to the whole number.

1.25 rounds to 1
-2.69 round to -3

so the answer is 1 + (-3)

Just turn the whole gym into pie