A can complete a project in 30 days and B can complete the same project in 30 days. If A and B start working on the project together and A quits 10 days before the project is completed, in how many days will the project be completed? Choose one.
A) 18 days	B) 27 days	C) 26.67 days	D) 5 days	E) 12 days
Let X = the number of days taken to complete the project.   The amount of work done by A is (x-10) * (1/20).   The amount of work done by B is (x) * (1/30).   (1/30)*(x-10) + (1/30)*(x) = 1   (x/30) + (x/30) - (10/30) = 1   2x/30 = 1/3   x =5   Therefore, the answer is 5 days: 5.
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A can complete a project in 30 days and B can complete the same project in 30 days. If A and B start working on the project together and A quits 10 days before the project is completed, in how many days will the project be completed?