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'.

[EX Q]: Problem: if ( x + 3 ) ^ 2 / ( 2 x + 15 ) = 3 , then the difference between the two possible values of x is : 
Options: a ) 8 , b ) 10 , c ) 12 , d ) 14 , e ) 16
[EX A]: c

[EX Q]: Problem: a dishonest dealer claims to sell a product at its cost price . he uses a counterfeit weight which is 20 % less than the real weight . further greed overtook him and he added 15 % impurities to the product . find the net profit percentage of the dealer ? 
Options: a ) 46.85 % , b ) 43.75 % , c ) 50 % , d ) 56.25 % , e ) 36 %
[EX A]: b

[EX Q]: Problem: an alloy of copper and zinc contains copper and zinc in the ratio 5 : 3 . another alloy of copper and zinc contains copper and zinc in the ratio 1 : 7 . in what ratio should the two alloys be mixed so that the resultant alloy contains equal proportions of copper and zinc ? 
Options: a ) 1 : 5 , b ) 7 : 3 , c ) 5 : 3 , d ) 3 : 1 , e ) 4 : 3
[EX A]:
d