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: the average of 6 quantities is 8 . the average of 4 of them is 5 . what is the avg . of the remaining 2 numbers ? 
Options: a ) 11 , b ) 12 , c ) 13 , d ) 14 , e ) 15
[EX A]: d

[EX Q]: Problem: jacob is 39 years old . he is 3 times as old as his brother . how old will jacob be when he is twice as old ? 
Options: a ) 63 , b ) 64 , c ) 65 , d ) 76 , e ) 67
[EX A]: c

[EX Q]: Problem: the sum of the present ages of two persons a and b is 45 . if the age of a is twice that of b , find the sum of their ages 5 years hence ? 
Options: a ) 55 , b ) 60 , c ) 70 , d ) 80 , e ) 90
[EX A]:
a