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'.

Problem: if the cost price of 50 articles is equal to the selling price of 20 articles , then the gain or loss percent is ? 
Options: a ) 16 , b ) 127 , c ) 12 , d ) 18 , e ) 150
e

Problem: what profit percent is made by selling an article at a certain price , if by selling at 1 / 3 rd of that price , there would be a loss of 20 % ? 
Options: a ) 140 % , b ) 29 % , c ) 70 % , d ) 27 % , e ) 28 %
a

Problem: peter invested a certain sum of money in a simple interest bond whose value grew to $ 400 at the end of 3 years and to $ 600 at the end of another 2 years . what was the rate of interest in which he invested his sum ? 
Options: a ) 100 % , b ) 12.5 % , c ) 67 % , d ) 25 % , e ) 33 %

a