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: jacob is 39 years old . he is 3 times as old as his brother . how old will jacob be when he is twice as old ? 
Options: a ) 63 , b ) 64 , c ) 65 , d ) 76 , e ) 67

A: c
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Q: Problem: if a number x is 10 % less than another number y and y is 10 % more than 125 , then x is equal to 
Options: a ) 143 , b ) 150 , c ) 123.75 , d ) 140.55 , e ) none

A: c
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Q: Problem: ( ( ( 13 ! ) ^ 16 ) - ( ( 13 ! ) ^ 8 ) ) / ( ( ( 13 ! ) ^ 8 ) + ( ( 13 ! ) ^ 4 ) ) = a then what is the units digit for a / ( ( 13 ! ) ^ 4 ) = 
Options: a ) 7 , b ) 8 , c ) 9 , d ) 6 , e ) 5

A:
c
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