You can do calculations with times in Excel as if they were numbers (they are stored internally as numbers, 1 = 1 day). So with 09:30 in A1
will give you 8 x 09:30.
The problem is that the result will show as 04:00 because Excel displays a Time and not a Duration by only displaying the decimal part of the number. You can get around this by setting a Custom format for the result cell of [h]:mm and the correct result (76:00) will be displayed.