Task: Question Answering
Input (English): Problem: how many liters of oil at rs . 40 per liter should be mixed with 240 liters of a second variety of oil at rs . 60 per liter so as to get a mixture whose cost is rs . 52 per liter ? 
Options: a ) 120 , b ) 150 , c ) 160 , d ) 180 , e ) 200
Output (English): c