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'.

[Q]: Problem: some of 10 % - intensity red paint is replaced with 20 % solution of red paint such that the new paint intensity is 15 % . what fraction of the original paint was replaced ? 
Options: a ) 2 / 5 , b ) 2 / 3 , c ) 1 / 2 , d ) 1 / 3 , e ) 1 / 5
[A]: c


[Q]: Problem: a dishonest dealer professes to sell goods at the cost price but uses a weight of 990 grams per kg , what is his percent ? 
Options: a ) 1.01 % , b ) 25 % , c ) 22 % , d ) 29 % , e ) 45 %
[A]: a


[Q]: Problem: how many liters of water must be added to 20 liters of milk and water containing 10 % water to make it 60 % water ? 
Options: a ) 12 , b ) 15 , c ) 18 , d ) 22 , e ) 25
[A]:
e