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

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 ?
$ 22.72

Problem: last year elaine spent 20 % of her annual earnings on rent . this year she earned 35 % more than last year and she spent 30 % of her annual earnings on rent . the amount she spent on rent this year is what percent of the amount spent on rent last year ?
202.5

Problem: if 30 men take 15 days to to complete a job , in how many days can 25 men finish that work ?

18