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'.

[Q]: Problem: a father said to his son , ` ` i was as old as you are at the present at the time of your birth ' ' . if the father ' s age is 52 years now , the son ' s age 5 years back was : 
Options: a ) a ) 14 , b ) b ) 67 , c ) c ) 56 , d ) d ) 21 , e ) e ) 34
[A]: d


[Q]: Problem: find the ones digit of 73 ^ 356 
Options: a ) 1 , b ) 5 , c ) 6 , d ) 7 , e ) 9
[A]: a


[Q]: Problem: when 2 is added to half of one - third of one - fifth of a number , the result is one - fifteenth of the number . find the number ? 
Options: a ) 40 , b ) 65 , c ) 73 , d ) 60 , e ) 80
[A]:
d