30 hours because if there are 6 people working, each person will do 150 bags. it takes 300 minutes for each person to do 150 bags (150*2). it will take 1800 minutes for 6 people to do 900 bags (300*6). divide 1800 by 60 (minutes) and you get 30 hours
It has to do with the unit circle, I think it is A because it should be 2(0+ (-1)) but I would probably wait for someone to come behind me and explain it better sorry couldn't help more
