Mysql get last working day (satursday) of previous month

SET @dt = '2012-07-01'; -- Last day of the previous month (June 2012) was a Saturday

 SELECT CASE DAYOFWEEK(LAST_DAY(@dt-INTERVAL 1 MONTH)) 
        WHEN 1 THEN LAST_DAY(@dt-INTERVAL 1 MONTH)-INTERVAL 2 DAY 
        WHEN 7 THEN LAST_DAY(@dt-INTERVAL 1 MONTH)-INTERVAL 1 DAY 
        ELSE LAST_DAY(@dt-INTERVAL 1 MONTH)
        END x;