Question

Joseph and Chandra are cleaning their house, which has 12 rooms, each about the same size. If joseph cleans them by himself, it takes him 6 hours. if Chandra cleans them by herself, it takes her 12 hours. If they work together, how many rooms will Chandra clean and how many will Joseph clean?

Answer 1

no. of rooms cleaned in 1 hour by both of them: 1/6 +1/12 =1/4
so, total hours to clean house if they work together = 4 hours
in 4 hours, Joseph cleans 8 rooms, and Chandra cleans 4 rooms