Since production, sales and service are unified in the selling price, it is difficult to divide other expenses, such as personnel salary, rent, taxes and fees, water and electricity expenses, operation and management expenses, etc., in addition to the cost of raw materials (main ingredients, ingredients and seasonings) and fuel. Therefore, the traditional custom of catering industry is that the product cost is only the cost of main ingredients, ingredients, spices and fuel. Operating expenses are expressed in other percentages, for example, 30%, 40%, 50% and 60% of gross profit.