Question

Mrs. Sanders can clean the windows of her house in

3 hours. Her daughter can clean the windows in 6 hours.
How long will it take them to clean the windows if they
work together?

Answer 1

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Answer:

2 hours

Explanation:

Mrs. Sanders cleans 1/3 of the windows per hour. Her daughter cleans 1/6 of the windows per hour. Working together, they clean 1/3 +1/6 = 1/2 of the windows per hour.

It will take them 2 hours to finish when they work together.