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: a number increased by 20 % gives 480 . the number is ? 
Options: a ) 200 , b ) 300 , c ) 400 , d ) 500 , e ) 600
[EX A]: c

[EX Q]: Problem: what is the rate percent when the simple interest on rs . 4000 amount to rs . 320 in 2 years ? 
Options: a ) 4 % , b ) 4.1 % , c ) 4.2 % , d ) 4.3 % , e ) 4.5 %
[EX A]: a

[EX Q]: Problem: the price of a t . v . set worth rs . 15000 is to be paid in 20 installments of rs . 1500 each . if the rate of interest be 6 % per annum , and the first installment be paid at the time of purchase , then the value of the last installment covering the interest as well will be ? 
Options: a ) 29997 , b ) 28088 , c ) 13500 , d ) 19000 , e ) 2799
[EX A]:
c