The task is to generate the correct answer for a given math problem.
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Question: Problem: a customer went to a shop and paid a total of $ 40 , out of which $ 1.28 was for sales tax on taxable purchases . if the tax rate was 8 % , then what was the cost of the tax free items ?

Answer: $ 22.72


Question: Problem: virginia , adrienne , and dennis have taught history for a combined total of 96 years . if virginia has taught for 9 more years than adrienne and for 12 fewer years than dennis , for how many years has dennis taught ?

Answer: 4


Question: Problem: 8 : 18 : : 24 : ?

Answer:
38