Task: Question Answering
Input (English): Problem: martin bought 10 concert tickets , some at the full price of $ 2.00 per ticket , and some at a discounted price of $ 1.60 per ticket . if he spent a total of $ 18.00 , how many discounted tickets did he buy ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7
Output (English): c