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

[EX Q]: Problem: a group of men decided to do a work in 55 days , but 15 of them became absent . if the rest of the group did the work in 60 days , find the original number of men ?
[EX A]: 180

[EX Q]: Problem: robert ' s salary was decreased by 20 % and subsequently increased by 20 % . how much percentage does he lose ?
[EX A]: 4 %

[EX Q]: Problem: if $ 5,000 is invested in an account at a simple annual rate of r percent , the interest is $ 250 . when $ 16,000 is invested at the same interest rate , what is the interest from the investment ?
[EX A]:
$ 800