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: the sum of ages of 5 children born at the intervals of 3 years each is 80 years . what is the age of the youngest child ? 
Options: a ) 3 years , b ) 4 years , c ) 6 years , d ) 7 years , e ) 10 years
[A]: e


[Q]: Problem: drum x is 1 / 2 full of oil and drum y , which has twice the capacity of drum x , is 1 / 5 full of oil . if all of the oil in drum x is poured into drum y , then drum y will be filled to what capacity ? 
Options: a ) 3 / 10 , b ) 7 / 10 , c ) 9 / 10 , d ) 9 / 20 , e ) 13 / 20
[A]: d


[Q]: Problem: a man whose speed is 6.5 kmph in still water rows to a certain upstream point and back to the starting point in a river which flows at 2.5 kmph , find his average speed for the total journey ? 
Options: a ) 1 kmph , b ) 5 kmph , c ) 5.5 kmph , d ) 4 kmph , e ) 7 kmph
[A]:
c