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: after 6 games , team b had an average of 75 points per game . if it got only 47 points in game 7 , how many more points does it need to score to get its total above 500 ? 
Options: a ) 5 , b ) 4 , c ) 7 , d ) 3 , e ) 8
Example Output: d

Example Input: Problem: if x dollars is invested at 10 percent for one year and y dollars is invested at 8 percent for one year , the annual income from the 10 percent investment will exceed the annual income from the 8 percent investment by $ 83 . if $ 2,000 is the total amount invested , how much is invested at 8 percent ? 
Options: a ) $ 550 , b ) $ 650 , c ) $ 750 , d ) $ 850 , e ) $ 950
Example Output:
b