It will take mr. warner 15 1/2 hours to install a fence. each day he works 1 1/3 hours on the fence. after he finished working on the fence yesterday he had 3 1/2 hours of work left to do. for how many days has mr. warner worked on the fence?

15.5-3.5=12. this is how many hours he has worked already.

12/1⅓=9. this is because how many hours he has worked per how many hours he worked per day to show how many days he worked

the answer is 9 days.

12hours * 1day/1⅓ hours
^^ignore that if it doesn't make sense, but basically the hours will cancel and you'd be left with days as your only unit to show why you would divide 12 by 1⅓

hope this helped!