Task: Question Answering
Input (English): Problem: a dishonest person wants to make a profit on the selling of milk . he would like to mix water ( costing nothing ) with milk costing 33 $ per litre so as to make a profit of 60 % on cost when he sells the resulting milk and water mixture for 36 $ . in what ratio should he mix the water and milk ? 
Options: a ) 7 : 15 , b ) 7 : 10 , c ) 7 : 8 , d ) 7 : 4 , e ) 7 : 2
Output (English): a