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: a man is 20 years older than his son . in two years , his age will be twice the age of his son . the present age of the son is ? 
Options: a ) 11 , b ) 25 , c ) 27 , d ) 18 , e ) 91
[EX A]: d

[EX Q]: Problem: 5357 x 51 = ? 
Options: a ) 273232 , b ) 273243 , c ) 273247 , d ) 273250 , e ) 273207
[EX A]: e

[EX Q]: Problem: a man is 37 years older than his son . in two years , his age will be twice the age of his son . the present age of this son is 
Options: a ) 78 years , b ) 22 years , c ) 88 years , d ) 35 years , e ) 65 years
[EX A]:
d