TASK DEFINITION: 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'.
PROBLEM: Problem: a man buys an article for $ 10 . and sells it for $ 30 . find the gain percent ? 
Options: a ) 25 % , b ) 50 % , c ) 20 % , d ) 150 % , e ) 300 %

SOLUTION: e

PROBLEM: Problem: the population of a town is 10000 . it increases annually at the rate of 20 % p . a . what will be its population after 1 year ? 
Options: a ) 12300 , b ) 12350 , c ) 12000 , d ) 12500 , e ) 12600

SOLUTION: c

PROBLEM: Problem: an empty fuel tank with a capacity of 200 gallons was filled partially with fuel a and then to capacity with fuel b . fuel a contains 12 % ethanol by volume and fuel b contains 16 % ethanol by volume . if the full fuel tank contains 30 gallons of ethanol , how many gallons of fuel a were added ? 
Options: a ) 160 , b ) 150 , c ) 100 , d ) 80 , e ) 50

SOLUTION:
e