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'.
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Question: Problem: if 3 x 5 y = 5 and x / x + y = 5 / 7 , then what is the value of x y ?
Options: a ) 9 , b ) 6 , c ) 4 , d ) 3 , e ) none of these

Answer: d

Question: Problem: gold is 10 times as heavy as water and copper is 6 times as heavy as water . in what ratio should these be mixed to get an alloy 8 times as heavy as water ?
Options: a ) 3 : 2 , b ) 1 : 1 , c ) 3 : 1 , d ) 5 : 2 , e ) 4 : 3

Answer: b

Question: Problem: suppose that f ( x ) is a function such that for every real number x , i ) f ( x ) + f ( 1 - x ) = 10 and ( ii ) f ( 1 + x ) = 3 + f ( x ) . then f ( x ) + f ( - x ) must equal
Options: a ) 7 , b ) 9 , c ) 10 , d ) 11 , e ) 12

Answer:
a