In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: of 600 surveyed students , 20 % of those who read book a also read book b and 25 % of those who read book b also read book a . if each student read at least one of the books , what is the difference between the number of students who read only book a and the number of students who read only book b ? 
Options: a ) 20 , b ) 25 , c ) 30 , d ) 35 , e ) 75
[EX A]: e

[EX Q]: Problem: jar a has 6 % more marbles than jar b . what percent of marbles from jar a need to be moved into jar b so that both jars have equal marbles ? 
Options: a ) 2.8 % , b ) 3.0 % , c ) 3.2 % , d ) 3.4 % , e ) 3.6 %
[EX A]: a

[EX Q]: Problem: a man buys 56 pens at marked price of 46 pens from a whole seller . if he sells these pens giving a discount of 1 % , what is the profit percent ? 
Options: a ) 7.6 % , b ) 7.7 % , c ) 20.52 % , d ) 23.62 % , e ) 27.82 %
[EX A]:
c