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 difference of two numbers is 11 and one - fifth of their sum is 9 . find the numbers . 
Options: a ) 28 and 17 , b ) 27 and 18 , c ) 25 and 15 , d ) 27 and 15 , e ) 25 and 18

Ex Output:
a


Ex Input:
Problem: what is the average of first 21 multiples of 5 ? 
Options: a ) a ) 70 , b ) b ) 77 , c ) c ) 55 , d ) d ) 81 , e ) e ) 82

Ex Output:
c


Ex Input:
Problem: in a mixture 60 litres , the ratio of milk and water 2 : 1 . if this ratio is to be 1 : 2 , then the quanity of water to be further added is 
Options: a ) 50 liters , b ) 55 liters , c ) 60 liters , d ) 70 liters , e ) 75 liters

Ex Output:

c