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

[Q]: Problem: the ratio between the sale price and the cost price of an article is 12 : 7 . what is the ratio between the profit and the cost price of that article ?
[A]: 5 : 7


[Q]: Problem: the ratio of the radius of two circles is 1 : 3 , and then the ratio of their areas is ?
[A]: 1 : 9


[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