Question 370282
Painter takes 20 hours
so he will do 1/20 of the job in 1 hour
..
Apprentice takes 45 hours
so he does 1/45 of the job in 1 hour.
..
together they do 1/20 + 1/45 of the job in 1 hour
=(9+4)/180 
=13/180 of the job in 1 hour
so they will together take 180/13 hours to do the job
..
13.8 hours
...
m.ananth@hotmail.ca