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'.

Ex Input:
Problem: the average marks of a class of 30 students is 40 and that of another class of 50 students is 60 . find the average marks of all the students ? 
Options: a ) 82.5 , b ) 52.9 , c ) 52.2 , d ) 52.5 , e ) 52.7

Ex Output:
d


Ex Input:
Problem: x varies inversely as square of y . given that y = 3 for x = 1 . the value of x for y = 7 will be equal to : 
Options: a ) 3 , b ) 6 , c ) 1 / 9 , d ) 1 / 3 , e ) 9 / 49

Ex Output:
e


Ex Input:
Problem: for the past n days , the average ( arithmetic mean ) daily production at a company was 60 units . if today ' s production of 90 units raises the average to 65 units per day , what is the value of n ? 
Options: a ) 30 , b ) 18 , c ) 10 , d ) 9 , e ) 5

Ex Output:

e