It says to round to the nearest whole number.
Bailey: The number 35.78 is closer to 36 seconds than 35, so 35.78 rounded to the nearest whole number is 36.
Elena: The number 39.51 is closer to 40 seconds than 39, so 39.51 rounded to the nearest whole number is 40.
Next it says to find how many seconds Bailey won the race by.
40 - 36 = 4 seconds
Bailey won the race by 4 seconds.
Hope this helped :))