In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: the c . p of 20 books is equal to the s . p of 30 books . find his gain % or loss % ? 
Options: a ) 63.33 % , b ) 34.33 % , c ) 33.33 % , d ) 31.33 % , e ) 36.33 %
[EX A]: c

[EX Q]: Problem: what profit percent is made by selling an article at a certain price , if by selling at 4 / 5 rd of that price , there would be a loss of 20 % ? 
Options: a ) 0 % , b ) 29 % , c ) 70 % , d ) 27 % , e ) 28 %
[EX A]: a

[EX Q]: Problem: in an office , 60 percent of the workers have at least 5 years of service , and a total of 16 workers have at least 10 years of service . if 90 percent of the workers have fewer than 10 years of service , how many of the workers have at least 5 but fewer than 10 years of service ? 
Options: a ) 96 , b ) 64 , c ) 50 , d ) 144 , e ) 160
[EX A]:
a