If jorge worked a total of 30.5 hours how many hours are missing

If you would like to know how many hours per one specific week are missing and Jorge has to work 40 hours per week (8 hours per day, 5 working days), you have to subtract 30.5 hours from 40 hours to get the result.

40 - 30.5 = 9.5

The result would be that 9.5 hours are missing (probably one whole day = 8 hours and 1.5 hours from one another day).