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: how many pounds of salt at 50 cents / lb must be mixed with 40 lbs of salt that costs 25 cents / lb so that a merchant will get 20 % profit by selling the mixture at 48 cents / lb ? 
Options: a ) 20 , b ) 15 , c ) 40 , d ) 60 , e ) 25
d

Problem: the true discount on a bill due 9 months hence at 16 % per annum is rs . 150 . the amount of the bill is 
Options: a ) 1200 , b ) 1764 , c ) 1400 , d ) 1354 , e ) none of these
c

Problem: john had a stock of 1400 books in his bookshop . he sold 75 on monday , 50 on tuesday , 64 on wednesday , 78 on thursday and 135 on friday . what percentage of the books were not sold ? 
Options: a ) 50.4 % , b ) 71.3 % , c ) 66.5 % , d ) 34.9 % , e ) 43.5 %

b