$39$

There are two common forms of a compressed workweek:

Select one:

four $10-$hour days per week, and nine days over two weeks three $12-$hour days per week, and nine days over two weeks four $10-$hour days per week, and $10$ days over two weeks three $12-$hour days per week, and $10$ days over two weeks two days on$,$ three days off; three days on$,$ two days off