Why do characters often have complex motivations in stories

Characters often have complex motivations in stories because without an interesting plot or without any true meaning given to a characters actions, the story would be meaningless. So if you think about reading a book where the main character hopes to save the world rather than go to Tescos and buy something, there will obviously be a big difference between how the story makes you, the reader, feel like.

He bought 4 boxes

Explanation:

Since the number of initial nails is

Initial number of nails = n boxes * 24 nails/box

Then

number of remaining nails = initlal nails - nails spent

62 = n*24-34

n = (62+34)/24 = 4 boxes

Therefore he bought 4 boxes