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: working alone , printers x , y , and z can do a certain printing job , consisting of a large number of pages , in 12 , 16 , and 18 hours , respectively . what is the ratio of the time it takes printer x to do the job , working alone at its rate , to the time it takes printers y and z to do the job , working together at their individual rates ? 
Options: a ) 4 / 11 , b ) 1 / 2 , c ) 15 / 22 , d ) 144 / 17 , e ) 11 / 4
d

Problem: a number is doubled and 6 is added . if resultant is trebled , it becomes 72 . what is that number 
Options: a ) 8 , b ) 10 , c ) 9 , d ) 14 , e ) 16

c