Task: Question Answering
Input (English): Problem: the prices of tea and coffee per kg were the same in june . in july the price of coffee shot up by 20 % and that of tea dropped by 20 % . if in july , a mixture containing equal quantities of tea and coffee costs 90 / kg . how much did a kg of coffee cost in june ? 
Options: a ) 50 , b ) 60 , c ) 80 , d ) 90 , e ) 120
Output (English): d