Task: Question Answering
Input (English): Problem: a producer of tea blends two varieties of tea from two tea gardens one costing rs 18 per kg and another rs 20 per kg in the ratio 5 : 3 . if he sells the blended variety at rs 21 per kg , then his gain percent is 
Options: a ) 12 % , b ) 13 % , c ) 14 % , d ) 15 % , e ) 16 %
Output (English): a