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

Q: Problem: a is half good a work man as b and together they finish a job in 14 days . in how many days working alone b finish the job ?

A: 21
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Q: Problem: how much interest will $ 10,000 earn in 9 months at an annual rate of 4 % ?

A: $ 300
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Q: Problem: in a group of cows and chickens , the number of legs was 12 more than twice the number of heads . the number of cows was :

A:
6
****