together to paint a similar house?
This one took me some time to figure out the best way to complete.
First think about the rate it takes each of them to work in what fraction of a house they can complete in an hour.
profession: 1/6 houses/hr
apprentice: 1/9 houses/hr
Next, since they will be working together combine their painting speed:
(1/6)+(1/9) = 5/18
That means working together they can complete 5 houses in 18 hours.
So 1 house can be done in 18/5 or 3.6hrs.
Note: Since time doesn't uses decimals 0.6hrs is the equivalent of 36 minutes, so the answer can be written as 3 hours and 36 minutes.
I hope this is understandable, let me know if you need more help.