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: a shopkeeper sold an article at $ 100 with 10 % profit . then find its cost price ? 
Options: a ) $ 120 , b ) $ 100 , c ) $ 91 , d ) $ 72 , e ) $ 69
c

Problem: the effective annual rate of interest corresponding to a nominal rate of 6 % per annum payable half - yearly is : 
Options: a ) 6.09 % , b ) 6.08 % , c ) 6.1 % , d ) 6.07 % , e ) 6.05 %
a

Problem: john makes $ 50 a week from his job . he earns a raise and now makes $ 80 a week . what is the % increase ? 
Options: a ) 16 % , b ) 16.66 % , c ) 17.9 % , d ) 18.12 % , e ) 60 %

e