There is a large supermarket. What can I do to make money in it?

Purchasing is the most profitable, but it is generally impossible without experience. If it is not a hard relationship, ordinary technical work can't be done. I suggest you go to the supermarket to collect garbage. Don't look down on this. If I give it to you at a low price, you can buy a mid-range car with a year's income. If there are many shops, it will be even more impressive.