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'.

[EX Q]: Problem: if two of the 4 expressions x + y , x + 5 y , x - y , and 5 x - y are chosen at random , what is the probability w that their product will be of the form of x ^ 2 - ( by ) ^ 2 , where b is an integer ? 
Options: a ) 1 / 2 , b ) 1 / 3 , c ) 1 / 4 , d ) 1 / 5 , e ) w = 1 / 6
[EX A]: e

[EX Q]: Problem: the average of 5 quantities is 9 . the average of 3 of them is 4 . what is the average of remaining 2 numbers ? 
Options: a ) 16.5 , b ) 10 , c ) 8 , d ) 9.5 , e ) none of these
[EX A]: a

[EX Q]: Problem: sum of 24 odd numbers is ? 
Options: a ) 572 , b ) 573 , c ) 574 , d ) 575 , e ) 576
[EX A]:
e