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

[Q]: Problem: the compound interest on $ 30,000 at 7 % p . a is $ . 4347 . find out the period ( in years ) ?
[A]: 2


[Q]: Problem: a student chose a number , multiplied it by 2 , then subtracted 138 from the result and got 102 . what was the number he chose ?
[A]: 120


[Q]: Problem: a is twice as good a workman as b and together they complete a work in 12 days . in how many days a alone can do the work ?
[A]:
3