Task: Question Answering
Input (English): Problem: the average weight of a group of 30 friends increases by 10 kg when the weight of additional 30 friends was added . if average weight of the whole group after including the additional 30 members is 40 kg , what is the average weight of the additional friends ? 
Options: a ) 50 kg , b ) 60 kg , c ) 61 kg , d ) 62 kg , e ) 91 kg
Output (English): a