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 x : y = 3 : 5 , find the value of ( 2 x + 4 y ) : ( 3 x – y ) 
Options: a ) 13 : 2 , b ) 11 : 2 , c ) 13 : 3 , d ) 13 : 4 , e ) 13 : 5
[EX A]: a

[EX Q]: Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab . 
Options: a ) 9 , b ) 2 , c ) 3 , d ) 7 , e ) 12
[EX A]: c

[EX Q]: Problem: if the remainder is 10 when positive integer n is divided by 14 , what is the remainder when n is divided by 7 ? 
Options: a ) 0 , b ) 1 , c ) 2 , d ) 3 , e ) 4
[EX A]:
d