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: if - 3 x + 2 y = 28 and 3 x + 6 y = 84 , what is the product of x and y ? 
Options: a ) 264 . , b ) 428 , c ) 0 , d ) 462 , e ) 642
Example Output: c

Example Input: Problem: a car ferry can hold up to 70 tons of cargo . what is the greatest number of vehicles that the ferry can carry if half the vehicles are cars with an average ( arithmetic mean ) weight of 0.75 tons and half of the vehicles are trucks with an average ( arithmetic mean ) weight of 4 tons ? 
Options: a ) 14 , b ) 20 , c ) 28 , d ) 32 , e ) 36
Example Output: c

Example Input: Problem: a store owner estimates that the average price of type a products will increase by 25 % next year and that the price of type b products will increase by 20 % next year . this year , the total amount paid for type a products was $ 4500 and the total price paid for type b products was $ 8300 . according to the store owner ' s estimate , and assuming the number of products purchased next year remains the same as that of this year , how much will be spent for both products next year ? 
Options: a ) $ 14,755 , b ) $ 15,585 , c ) $ 16,000 , d ) $ 16,225 , e ) $ 17,155
Example Output:
b