Janet can do a job in 3 hours while Garry can do the same job in 2 hours. If Janet works for an hour before Garry helps her, how long will it take them to finish the job together?

Janet can do a job in 3 hours while Garry can do the same job in 2 hours. If Janet works for an hour before Garry helps her, how long will it take them to finish the job together?