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: at what rate percent per annum will the simple interest on a sum of money be 2 / 5 of the amount in 10 years ? 
Options: a ) 4 % , b ) 74 % , c ) 64 % , d ) 74 % , e ) 94 %
a

Problem: on a sum of money , the simple interest for 2 years is rs . 324 , while the compound interest is rs . 340 , the rate of interest being the same in both the cases . the rate of interest is 
Options: a ) 15 % , b ) 14.25 % , c ) 9.87 % , d ) 10.5 % , e ) 11.5 %
c

Problem: martin bought 10 concert tickets , some at the full price of $ 2.00 per ticket , and some at a discounted price of $ 1.60 per ticket . if he spent a total of $ 18.40 , how many discounted tickets did he buy ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7

b