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'.

[Q]: Problem: if 40 % of a certain number is 160 , then what is 30 % of that number ? 
Options: a ) 270 , b ) 380 , c ) 120 , d ) 360 , e ) 180
[A]: c


[Q]: Problem: in a certain pond , 80 fish were caught , tagged , and returned to the pond . a few days later , 50 fish were caught again , of which 2 were found to have been tagged . if the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond , what is the approximate number of fish in the pond ? 
Options: a ) 400 , b ) 625 , c ) 1,250 , d ) 2,000 , e ) 10,000
[A]: d


[Q]: Problem: a merchant marks his goods up by 50 % and then offers a discount of 20 % on the marked price . what % profit does the merchant make after the discount ? 
Options: a ) 20 % , b ) 25 % , c ) 69 % , d ) 31 % , e ) 19 %
[A]:
a