The formulas of purchase price, selling price and profit in junior middle school mathematics are: selling price-purchase price = profit, selling price = purchase price+profit, etc. Profit is the business achievement of entrepreneurs, the comprehensive reflection of the business effect of enterprises and the concrete embodiment of their final results.

The essence of profit is the manifestation of enterprise profit and the labor achievement of all employees. Enterprises make profits by producing high-quality goods for the market. Compared with surplus value, profit is not only the same in quality, but also the same in quantity.