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'.

Problem: solve the equation for x : 8 x - 40 + 2 x = 5 + 10 - x 
Options: a ) 4 , b ) 10 , c ) 7 , d ) 5 , e ) 3
d

Problem: john found that the average of 15 numbers is 40 . if 12 is added to each number then the mean of number is ? 
Options: a ) 52 , b ) 45 , c ) 65 , d ) 78 , e ) 64
a

Problem: paul ' s income is 20 % less than rex ' s income , quentin ' s income is 20 % less than paul ' s income , and sam ' s income is 40 % less than paul ' s income . if rex gave 60 % of his income to sam and 40 % of his income to quentin , quentin ' s new income would be what fraction of sam ' s new income ? 
Options: a ) 26 / 27 , b ) 13 / 17 , c ) 13 / 19 , d ) 12 / 19 , e ) 11 / 19

a