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 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
Example Output: d

Example Input: Problem: find the value of ( 55 + 113 / 78 ) × 78 
Options: a ) 4423 , b ) 4403 , c ) 4413 , d ) 2403 , e ) 4375
Example Output: b

Example Input: Problem: how many positive integer solutions does the equation 2 x + 3 y = 100 have ? 
Options: a ) 50 , b ) 33 , c ) 16 , d ) 35 , e ) 14
Example Output:
c