I'm build a cursor to use for a report and need to repeat the same sum() many times. Is there a way to resuse a calculated field again?

This is an example, but I have to create hours and ratios for a dozen different time types:

Select sum(ts.nHours) as totalHours, ;
	Sum(IIF(ts.fk_timetype_id = 1, 1, 0)) As woHours, ;
        ** The following is repeating the totalHours and woHours sums
        ** is there a way resuse those calculated columns?
	Sum(IIF(ts.fk_timetype_id = 1, 1, 0)) / (sum(ts.nHours) / 100) As woRatio

TIA