In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Q: Problem: a certain number of horses and an equal number of men are going somewhere . half of the owners are on their horses ' back while the remaining ones are walking along leading their horses . if the number of legs walking on the ground is 40 , how many horses are there ? 
Options: a ) 8 , b ) 12 , c ) 14 , d ) 16 , e ) 18

A: a
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Q: Problem: a number whose fifth part increased by 7 is equal to its fourth part diminished by 7 is ? 
Options: a ) 160 , b ) 180 , c ) 200 , d ) 280 , e ) none

A: d
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Q: Problem: how many prime numbers are between 25 / 8 and 213 / 6 ? 
Options: a ) 6 , b ) 7 , c ) 8 , d ) 9 , e ) 10

A:
d
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