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: it takes 30 days to fill a laboratory dish with bacteria . if the size of the bacteria doubles each day , how long did it take for the bacteria to fill one sixteenth of the dish ? 
Options: a ) 16 days , b ) 26 days , c ) 27 days , d ) 28 days , e ) 29 days

A: b
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Q: Problem: solve the equation for x : 8 x - 40 + 2 x = 5 + 10 - x 
Options: a ) 4 , b ) 10 , c ) 7 , d ) 5 , e ) 3

A: d
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Q: Problem: a certain fraction is equivalent to 3 / 5 . if the numerator of the fraction is increased by 4 and the denominator is doubled , the new fraction is equivalent to 1 / 3 . what is the sum of the numerator and denominator of the original fraction ? 
Options: a ) 49 , b ) 35 , c ) 28 , d ) 56 , e ) 21

A:
d
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