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'.

[Q]: Problem: a is the hundreds digit of the 3 digit integer x , b is the tens digit of x , and c is the units digit of x . 4 a = 2 b = c , and a > 0 . what is the difference between the two greatest possible values of x ? tip : dont stop till you have exhausted all answer choices to arrive at the correct one . 
Options: a ) 124 , b ) 297 , c ) 394 , d ) 421 , e ) 842
[A]: a


[Q]: Problem: 12.1212 + 17.0005 - 9.1103 = ? 
Options: a ) 20.0015 , b ) 20.0105 , c ) 20.0115 , d ) 20.0114 , e ) none
[A]: d


[Q]: Problem: 998 x 998 = ? 
Options: a ) 996000 , b ) 1000000 , c ) 996004 , d ) 4000 , e ) 996008
[A]:
c