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: if 40 % of a number is greater than 80 % of 5 by 2 , what is the number ? 
Options: a ) 3 , b ) 15 , c ) 20 , d ) 2 , e ) 5

A: b
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Q: Problem: what percent of 120 are 90 ? 
Options: a ) 25 % , b ) 50 % , c ) 75 % , d ) 33 % , e ) 30 %

A: c
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Q: Problem: a tank contains 7,500 gallons of a solution that is 6 percent sodium chloride by volume . if 2,000 gallons of water evaporate from the tank , the remaining solution will be approximately what percent sodium chloride ? 
Options: a ) 5.18 % , b ) 6.18 % , c ) 7.18 % , d ) 8.18 % , e ) . 7 %

A:
d
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