Task: Question Answering
Input (English): Problem: a merchant gains or loses , in a bargain , a certain sum . in a second bargain , he gains 380 dollars , and , in a third , loses 70 . in the end he finds he has gained 250 dollars , by the 3 together . how much did he gain or lose bv the first ? 
Options: a ) 80 , b ) 60 , c ) - 60 , d ) - 70 , e ) none
Output (English): c