In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: the average age of a group of 10 persons was decreased by 3 years when one person , whose age was 42 years , was replaced by a new person . find the age of the new person ? 
Options: a ) 22 , b ) 18 , c ) 12 , d ) 88 , e ) 66
Example Output: c

Example Input: Problem: if x : y = 3 : 5 , find the value of ( 2 x + 4 y ) : ( 3 x – y ) 
Options: a ) 13 : 2 , b ) 11 : 2 , c ) 13 : 3 , d ) 13 : 4 , e ) 13 : 5
Example Output: a

Example Input: Problem: the wages earned by robin is 30 % more than that earned by erica . the wages earned by charles is 60 % more than that earned by erica . how much percent is the wages earned by charles more than that earned by robin ? 
Options: a ) 18.75 % , b ) 23 % , c ) 30 % , d ) 50 % , e ) 100 %
Example Output:
b