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: a man invests rs . 3,000 at the rate of 5 % per annum . how much more should he invest at the rate of 8 % , so that he can earn a total of 6 % per annum ? 
Options: a ) rs . 1200 , b ) rs . 1300 , c ) rs . 1500 , d ) rs . 2000 , e ) none of these
c

Problem: a person buys an article at rs . 500 . at what price should he sell the article so as to make a profit of 35 % ? 
Options: a ) 600 , b ) 887 , c ) 256 , d ) 654 , e ) 675
e

Problem: 120 students represent x percent of the boys at a school . if the boys at the school make up 30 % of the total school population of x students , what is x ? 
Options: a ) 120 , b ) 150 , c ) 180 , d ) 200 , e ) 250

d