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: in a group of ducks and cows , the total number of legs are 36 more than twice the number of heads . find the total number of cows . 
Options: a ) 12 , b ) 14 , c ) 16 , d ) 18 , e ) 20
[A]: d


[Q]: Problem: in a river flowing at 2 km / hr , a boat travels 40 km upstream and then returns downstream to the starting point . if its speed in still water be 6 km / hr , find the total journey time . 
Options: a ) 10 hours , b ) 12 hours , c ) 14 hours , d ) 15 hours , e ) none of these
[A]: d


[Q]: Problem: an employee ’ s annual salary was increased $ 5000 . if her new annual salary now equals $ 25000 what was the percent increase ? 
Options: a ) 15 % , b ) 80 % , c ) 20 % , d ) 22 % , e ) 24 %
[A]:
b