Task: Question Answering
Input (English): Problem: a certain fraction is equivalent to 2 / 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 difference of the numerator and denominator of the original fraction ? 
Options: a ) 49 , b ) 9 , c ) 28 , d ) 26 , e ) 21
Output (English): b