Do you mean 22:07? If so, then Marla went to bed in army time, which carries on from 12 o'clock. So 22:07 in army time is 10:07 PM, so Adelaide went to be earlier.
2207 is military time 2207 is 10 hours and 7minutes past 12 (12 would be 1200) So it was 10:07 pm when Marla went to bed so Adelaide went to bed earlier
The strange thing about the greatest integer function is that the number you are evaluating the function at is not actually the number unless its an integer. The rule is to round down, ALWAYS, if you are dealing with a value of x that is not an integer. In other words, you are NOT evaluating the function at 8.6, you have to round down to 8 and evaluate it there. 8 - 5 = 3
