Question 335808
Stan 3 hours 
so 1/3 of job he does in 1 hour.
Roger takes 2 hours
so he does 1/2 job in 1 hour.
..
together they do 1/3  + 1/2 job in 1 hour
=5/6 of the job in 1 hour.
so they will ake 6/5 hours to do the job.
1.2 hours
=1 hour 12 minutes