Minus The Weekend

If I was asked "How many days passed" the query is (below) and the answer is 33. But, then the curve ball is "can you subtract out the weekends?" and I said....well, I said I think so, but not sure how. So far, I have had no luck. Any advise?



SELECT
DATEDIFF ( dd , dbo.table_case.creation_time , dbo.table_close_case.close_date ) AS no_of_days,
dbo.table_case.id_number,
dbo.table_case.creation_time CreateTime,
dbo.table_close_case.close_date CloseDate

FROM
dbo.table_case,
dbo.table_close_case

WHERE
dbo.table_close_case.last_close2case=dbo.table_case.objid AND
dbo.table_case.id_number = '969382'

ORDER BY no_of_days ASC