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

Q: Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab .

A: 3
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Q: Problem: if s and t are both odd prime numbers ands < t , then how many different positive integer factors does 2 sthave ?

A: 8
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Q: Problem: a farmer grows broccoli in his farm that is in the shape of a square . each broccoli takes 1 square foot of area in his garden . this year , he has increased his output by 101 broccoli when compared to last year . the shape of the area used for growing the broccoli has remained a square in both these years . how many broccoli did he produce this year ?

A:
2601', 'c ) 1987', 'd ) 2000', 'e ) can not be determined'
****