Algebra II
posted by Lucy
Thomas can do a job in 4 hours. Julia can do the same job in 6 hours. How many hours will it take the two of them to do the job it they work together?

Ms. Sue
With two of them working together, then their times will be cut in half. Thomas can do it in 2 hours, while Julia does it in 3 hours.
(2 + 3)/ 2 = 2 1/2 hours 
drwls
Not quite.
Their combined rate of doing the rob is
1/4 job/h + 1/6 job/h = 5/12 job/h
5/12 job/h * T (hr) = 1 job
T = 12/5 = 2 2/5 hours 
Ms. Sue
Thanks, again  DrWLS. You're absolutely right  and I was wrong.

Ms. Sue
Maybe they stood around chatting for the additional 6 minutes? <G>
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