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: a shopkeeper sold 50 articles at the cost price of 60 articles . then find the profit % or lost % 
Options: a ) 20 % , b ) 22 % , c ) 25 % , d ) 30 % , e ) 35 %
[EX A]: a

[EX Q]: Problem: a man walking at a rate of 10 km / hr crosses a bridge in 3 minutes . the length of the bridge is ? 
Options: a ) 500 , b ) 650 , c ) 250 , d ) 111 , e ) 236
[EX A]:
a