Task: Question Answering
Input (English): Problem: in what ratio must tea of rs . 42 per kg be mixed with tea of rs . 50 per kg so that cost of mixture is rs . 45 per kg ? 
Options: a ) 5 : 3 , b ) 3 : 5 , c ) 2 : 3 , d ) 3 : 4 , e ) 1 : 2
Output (English): a