A commodity market has a _________ structure, if there is one seller of the commodity, the commodity has no substitute, and entry into the industry by another firm is prevented.
A boy leaves his school and travels 8 km towards the east. He takes a left turn and travels 6 km in that direction, and then turns towards the east and travels another 5 km. Finally, he turns right and travels 10 km. In which direction is he now from his school?