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: seed mixture x is 40 % ryegrass and 60 % bluegrass by weight ; seed mixture y is 25 % ryegrass and 75 % fescue . if a mixture of x and y contains 31 % ryegrass , what percent of the weight of the mixture is from mixture x ? 
Options: a ) 20 % , b ) 30 % , c ) 40 % , d ) 50 % , e ) 60 %
[EX A]: c

[EX Q]: Problem: a can complete a certain job in 19 days . b is 90 % more efficient than a . in how many days can b complete the same job ? 
Options: a ) 6 , b ) 6.25 , c ) 7 , d ) 7.5 , e ) 10
[EX A]: e

[EX Q]: Problem: a dishonest person wants to make a profit on the selling of milk . he would like to mix water ( costing nothing ) with milk costing 33 $ per litre so as to make a profit of 40 % on cost when he sells the resulting milk and water mixture for 36 $ . in what ratio should he mix the water and milk ? 
Options: a ) 1 : 20 , b ) 1 : 10 , c ) 17 : 8 , d ) 17 : 4 , e ) 17 : 60
[EX A]:
e