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: if the cost price of 50 articles is equal to the selling price of 20 articles , then the gain or loss percent is ? 
Options: a ) 16 , b ) 127 , c ) 12 , d ) 18 , e ) 150
[EX A]: e

[EX Q]: Problem: a car is purchased on hire - purchase . the cash price is $ 26 000 and the terms are a deposit of 10 % of the price , then the balance to be paid off over 60 equal monthly installments . interest is charged at 12 % p . a . what is the monthly installment ? 
Options: a ) $ 603 , b ) $ 624 , c ) $ 625 , d ) $ 626 , e ) $ 627
[EX A]: b

[EX Q]: Problem: the difference between c . i . and s . i . on an amount of $ 15,000 for 2 years is $ 54 . what is the rate of interest per annum ? 
Options: a ) 5 % , b ) 6 % , c ) 7 % , d ) 8 % , e ) 9 %
[EX A]:
b