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: a clock store sold a certain clock to a collector for 35 percent more than the store had originally paid for the clock . when the collector tried to resell the clock to the store , the store bought it back at 15 percent of what the collector had paid . the shop then sold the clock again at a profit of 65 percent on its buy - back price . if the difference between the clock ' s original cost to the shop and the clock ' s buy - back price was $ 105 , for how much did the shop sell the clock the second time ? 
Options: a ) $ 75.44 , b ) $ 88.23 , c ) $ 64.77 , d ) $ 54.32 , e ) $ 43.99
Example Output: e

Example Input: Problem: if x / y = 7 / 3 , then ( x + y ) / ( x - y ) = ? 
Options: a ) 5 , b ) 5 / 2 , c ) - 1 / 6 , d ) - 1 / 5 , e ) - 5
Example Output: b

Example Input: Problem: in what ratio must rice at $ 9.30 / kg be mixed with rice at $ 10.80 / kg so that the mixture is worth $ 10 / kg ? 
Options: a ) 1 : 3 , b ) 9 : 4 , c ) 8 : 7 , d ) 11 : 9 , e ) 11 : 7
Example Output:
c