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'.
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Question: 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 %

Answer: a


Question: Problem: from a total of 5 boys and 6 girls , how many 4 - person committees can be selected if the committee must have exactly 2 boys and 2 girls ? 
Options: a ) 16 , b ) 24 , c ) 60 , d ) 120 , e ) 150

Answer: e


Question: Problem: if a + b + c = 13 , then find the ab + bc + ca : 
Options: a ) 22 , b ) 99 , c ) 50 , d ) 29 , e ) 11

Answer:
c