The task is to generate the correct answer for a given math problem.

Q: Problem: a is twice as good a workman as b and they took 6 days together to do the work b alone can do it in .

A: 18 days
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Q: Problem: dhoni bought 5 toys with the average cost of $ 10 . if david also buys the sixth toy with the price of $ 16 , what is the average ( arithmetic mean ) price of those 6 toys ?

A: $ 1
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Q: Problem: find the simple interest on rs . 72,000 at 16 2 / 3 % per year for 9 months .

A:
9000
****