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: what profit percent is made by selling an article at a certain price , if by selling at 4 / 5 rd of that price , there would be a loss of 20 % ? 
Options: a ) 0 % , b ) 29 % , c ) 70 % , d ) 27 % , e ) 28 %

SOLUTION: a

PROBLEM: Problem: if 15 % of 40 is greater than 25 % of a number by 2 , the number is 
Options: a ) 14 , b ) 16 , c ) 18 , d ) 20 , e ) 22

SOLUTION: b

PROBLEM: Problem: in a certain math department , students are required to enroll in either calculus or trigonometry , each of which is offered in beginner and advanced courses . the number of students enrolled in trigonometry is 50 % greater than the number of students enrolled in calculus , and 70 % of calculus students are enrolled in the beginner course . if 4 / 5 of students are in the beginner courses , and one student is selected at random , what is the probability that an advanced trigonometry student is selected ? 
Options: a ) 8 % , b ) 16 % , c ) 20 % , d ) 24 % , e ) 40 %

SOLUTION:
a