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 7 a - 3 b = 10 b + 50 = - 12 b - 2 a , what is the value of 9 a + 9 b ? 
Options: a ) - 9 , b ) - 6 , c ) 0 , d ) 6 , e ) 9
[EX A]: c

[EX Q]: Problem: how many 3 - digit positive integers are there , where each digit is positive , and no 3 adjacent digits are same ? 
Options: a ) 1236 , b ) 504 , c ) 4096 , d ) 4608 , e ) 6561
[EX A]: b

[EX Q]: Problem: what must be added to each term of the ratio 4 : 15 , so that it may become equal to 3 : 4 ? 
Options: a ) 18 , b ) 29 , c ) 39 , d ) 49 , e ) 59
[EX A]:
b