In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[Q]: Problem: the tax on a commodity is diminished by 30 % but its consumption is increased by 15 % . find the decrease percent in the revenue derived from it ? 
Options: a ) 20 % , b ) 18 % , c ) 15 % , d ) 12 % , e ) 14 %
[A]: a


[Q]: Problem: how many numbers from 10 to 1000 are exactly divisible by 9 ? 
Options: a ) 100 , b ) 10 , c ) 11 , d ) 12 , e ) 14
[A]: a


[Q]: Problem: you collect pens . suppose you start out with 5 . mike gives you another 20 pens . since her father makes pens , cindy decides to double your pens . since you ' re nice , you give sharon 10 pens . how many pens do you have at the end ? 
Options: a ) 39 , b ) 40 , c ) 41 , d ) 42 , e ) 43
[A]:
b