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: the product of a and b is equal to 12 more than twice the sum of a and b . if b = 10 , what is the value of b - a ? 
Options: a ) 2 , b ) 5 , c ) 7 , d ) 6 , e ) 35
[EX A]: d

[EX Q]: Problem: when the positive integer x is divided by 9 , the remainder is 5 . what is the remainder when 5 x is divided by 9 ? 
Options: a ) 0 , b ) 1 , c ) 3 , d ) 4 , e ) 7
[EX A]: e

[EX Q]: Problem: let s be the set of all positive integers that , when divided by 8 , have a remainder of 5 . what is the 81 th number in this set ? 
Options: a ) 605 , b ) 608 , c ) 613 , d ) 616 , e ) 645
[EX A]:
e