Task: Question Answering
Input (English): Problem: in what ratio should a variety of rice costing rs . 7 per kg be mixed with another variety of rice costing rs . 14.50 per kg to obtain a mixture costing rs . 9.75 per kg ? 
Options: a ) 19 : 10 , b ) 19 : 11 , c ) 11 : 19 , d ) 12 : 18 , e ) 11 : 20
Output (English): b