In this task, you need to provide the correct option for a given problem from the provided options.

Q: Problem: on a certain farm the ratio of horses to cows is 5 : 1 . if the farm were to sell 15 horses and buy 15 cows , the ratio of horses to cows would then be 17 : 7 . after the transaction , how many more horses than cows would the farm own ? 
Options: a ) 30 , b ) 40 , c ) 50 , d ) 60 , e ) 70

A: c
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Q: Problem: how many kilograms of pure water is to be added to 100 kilograms of a 30 % saline solution to make it a 10 % saline solution . 
Options: a ) 100 , b ) 200 , c ) 300 , d ) 400 , e ) 500

A: b
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Q: Problem: if a student loses 6 kilograms , he will weigh twice as much as his sister . together they now weigh 126 kilograms . what is the student ' s present weight in kilograms ? 
Options: a ) 82 , b ) 84 , c ) 86 , d ) 88 , e ) 90

A:
c
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