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: among 7 numbers the average of first 4 numbers is 13 and the average of last 4 numbers is 15 . the sum of last 3 numbers is 55 . the square of the fourth number is equal to the last number then what is the last number ? 
Options: a ) 60 , b ) 52 , c ) 5 , d ) 25 , e ) 125
Example Output: d

Example Input: Problem: the ration of the father ’ s age to his son ’ s age is 7 : 3 . the product of their ages is 756 . the ratio of their ages after 6 years will be : 
Options: a ) 5 : 2 , b ) 2 : 1 , c ) 11 : 7 , d ) 13 : 9 , e ) none of these
Example Output: b

Example Input: Problem: for how many integer values of n will the value of the expression 4 n + 7 be an integer greater than 1 and less than 60 ? 
Options: a ) 10 , b ) 15 , c ) 8 , d ) 12 , e ) 20
Example Output:
b