Task: Question Answering
Input (English): Problem: the average weight of 3 packets a , b and c is 84 kg . another packet d added into the group and the average now becomes 80 kg . if another packet e , whose weight is 3 kg more than that of d , replaces a then the average weight of b , c , d and e becomes 79 kg . the weight of a is : 
Options: a ) 70 kg , b ) 72 kg , c ) 75 kg , d ) 80 kg , e ) none of these
Output (English): c