> please describe based on facts who writes a number into a computer that will be the price.
The person selling the goods, with a limited but sole-focused understanding of the competitors, stock coming in, stock going out, and forecasting does the best job he can to set the price that maximizes his individual profits
The person selling the goods, with a limited but sole-focused understanding of the competitors, stock coming in, stock going out, and forecasting does the best job he can to set the price that maximizes his individual profits