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'.

[Q]: Problem: when 1 / 20 % of 4,000 is subtracted from 1 / 10 of 4,000 , the difference is 
Options: a ) 50 , b ) 200 , c ) 380 , d ) 398 , e ) 400
[A]: d


[Q]: 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
[A]: c


[Q]: Problem: in an exam 80 % of the boys and 40 % of the girls passed . the number of girls who passed is 120 , which is 2 / 3 rd of the number of boys who failed . what is the total number of students who appeared for the exam ? 
Options: a ) 1200 , b ) 380 , c ) 3800 , d ) 2180 , e ) 3180
[A]:
a