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Tom can paint a fence in 5 hours and Huck can paint the same fence in 6 hours.
Tom starts painting the fence at 10 AM. He paints for an hour before Huck joins him at 11 AM.
Then they work together to finish painting the fence. At what time will they finish painting the fence?
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You are at serious danger, since you have INCORRECT SOLUTION from @josgarithmetic.
I came to get rid you of this danger: I brought a correct solution to you.
Working during 1 hour, Tom made 1/5 of the job; 4/5 of the job remained.
The combined rate of work of two boys is = = .
Working with the combined rate of work , two boys need
= = = = hours,
or about 2 hours and 11 minutes to complete the job.
So the job will be completed at about 11:00 am + 2 hours and 11 minutes, i.e. at about 1:11 pm. ANSWER
Solved.
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Ignore the post by @josgarithmetic for the sake of your safety,
since it is hopelessly wrong.