Mary can clean the house in 6 hours. Her younger sister Ruth can do the same job in 9 hours. In how many hours can they do the job if they work together?
1 Answer
Apr 10, 2018
Take the question in terms of fractions, not algebra, for a simpler approach.
Explanation:
In ONE hour, Mary can thus clean
In ONE hour, Ruth can thus clean
Therefore, together they can clean
To clean the entire house, they will take
