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: i sold a book at a profit of 10 % . had i sold it for $ 150 more , 15 % would have been gained . find the cost price ? 
Options: a ) $ 2000 , b ) $ 2500 , c ) $ 3000 , d ) $ 3120 , e ) $ 1540
c

Problem: an article is bought for rs . 560 and sold for rs . 340 , find the loss percent ? 
Options: a ) 36 % , b ) 38 % , c ) 16 % , d ) 39 % , e ) 12 %
d

Problem: the difference between c . i . and s . i . on an amount of rs . 15,000 for 2 years is rs . 294 . what is the rate of interest per annum ? 
Options: a ) 18 , b ) 12 , c ) 9 , d ) 14 , e ) 16

d