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: mary ' s income is 60 % more than tim ' s income and tim ' s income is 10 % less than juan ' s income . what % of juan ' s income is mary ' s income . 
Options: a ) 144 % , b ) b . 120 % , c ) 96 % , d ) 80 % , e ) 64 %
[EX A]: a

[EX Q]: Problem: ifaequals the sum of the even integers from 2 to 20 , inclusive , andbequals the sum of the odd integers from 1 to 19 , inclusive , what is the value of b - a ? 
Options: a ) - 10 , b ) 10 , c ) - 19 , d ) 20 , e ) 21
[EX A]: a

[EX Q]: Problem: a = { 0 , 1 , - 3 , 6 , - 8 } b = { - 1 , 2 , - 4 , 7 } if a is a number that is randomly selected from set a , and b is a number that is randomly selected from set b , what is the probability that ab > 0 ? 
Options: a ) 1 / 4 , b ) 1 / 3 , c ) 2 / 5 , d ) 4 / 9 , e ) 1 / 2
[EX A]:
c